Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–...Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2(1−x)Se2x alloys,synthesized by a simple and controllable chemical solution deposition method,are reported.The graded bandgaps,arising from the spatial grading of Se composition and thickness within a single domain,are tuned from 1.83 to 1.73 eV,leading to the formation of a homojunction with a builtin electric field.Consequently,a strong and sensitive gate-modulated photovoltaic effect is demonstrated,enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 mA W−1,a specific detectivity up to^10^11 Jones,and an on/off ratio up to^10^4.Remarkably,when illuminated by the lights ranging from 405 to 808 nm,the biased devices yield a champion photoresponsivity of 191.5 A W−1,a specific detectivity up to^1012 Jones,a photoconductive gain of 10^6–10^7,and a photoresponsive time in the order of^50 ms.These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions.展开更多
Mix-dimensional van der Waals heterostructures(vdWHs)have inspired worldwide interests and efforts in the field of ad-vanced electronics and optoelectronics.The fundamental understanding of interfacial charge transfer...Mix-dimensional van der Waals heterostructures(vdWHs)have inspired worldwide interests and efforts in the field of ad-vanced electronics and optoelectronics.The fundamental understanding of interfacial charge transfer is of vital import-ance for guiding the design of functional optoelectronic applications.In this work,type-Ⅱ0D-2D CdSe/ZnS quantum dots/MoS_(2)vdWHs are designed to study the light-triggered interfacial charge behaviors and enhanced optoelectronic performances.From spectral measurements in both steady and transient states,the phenomena of suppressed photolu-minescence(PL)emissions,shifted Raman signals and changed PL lifetimes provide strong evidences of efficient charge transfer at the 0D-2D interface.A series of spectral evolutions of heterostructures with various QDs overlapping concentrations at different laser powers are analyzed in details,which clarifies the dynamic competition between exciton and trion during an efficient doping of 3.9×10^(13)cm^(−2).The enhanced photoresponses(1.57×10^(4)A·W^(-1))and detectivities(2.86×10^(11)Jones)in 0D/2D phototransistors further demonstrate that the light-induced charge transfer is still a feasible way to optimize the performance of optoelectronic devices.These results are expected to inspire the basic understand-ing of interfacial physics at 0D/2D interfaces,and shed the light on promoting the development of mixed-dimensional op-toelectronic devices in the near future.展开更多
We report intrinsic photoconductivity studies on one of the least examined layered compounds,ZrS2.Few-atomic layer ZrS2 field-effect transistors were fabricated on the Si/SiO2 substrate and photoconductivity measureme...We report intrinsic photoconductivity studies on one of the least examined layered compounds,ZrS2.Few-atomic layer ZrS2 field-effect transistors were fabricated on the Si/SiO2 substrate and photoconductivity measurements were performed using both two-and four-terminal configurations under the illumination of 532 nm laser source.We measured photocurrent as a function of the incident optical power at several source-drain(bias)voltages.We observe a significantly large photoconductivity when measured in the multiterminal(four-terminal)configuration compared to that in the two-terminal configuration.For an incident optical power of 90 nW,the estimated photosensitivity and the external quantum efficiency(EQE)measured in two-terminal configuration are 0.5 A/W and 120%,respectively,under a bias voltage of 650 mV.Under the same conditions,the four-terminal measurements result in much higher values for both the photoresponsivity(R)and EQE to 6 A/W and 1400%,respectively.This significant improvement in photoresponsivity and EQE in the four-terminal configuration may have been influenced by the reduction of contact resistance at the metal-semiconductor interface,which greatly impacts the carrier mobility of low conducting materials.This suggests that photoconductivity measurements performed through the two-terminal configuration in previous studies on ZrS2 and other 2D materials have severely underestimated the true intrinsic properties of transition metal dichalcogenides and their remarkable potential for optoelectronic applications.展开更多
Near-infrared organic phototransistors have wide application prospects in many fields.The active materials with the high mobility and near-infrared response are critical to building high-performance near-infrared orga...Near-infrared organic phototransistors have wide application prospects in many fields.The active materials with the high mobility and near-infrared response are critical to building high-performance near-infrared organic phototransistors,which are scarce at present.Herein,a new charge transfer cocrystal using 5,7-dihydroindolo[2,3-b]carbazole(5,7-ICZ)as the donor and 2,2’-(benzo[1,2-b:4,5-b’]dithiophene-4,8-diylidene)dimalononitrile(DTTCNQ)as the acceptor is properly designed and prepared in a stoichiometric ratio(D:A=1:1),which not only displays a high electron mobility of 0.15 cm^(2)V^(-1)s^(-1) and very low dark current,but also can serve as the active layer materials in the region of near-infrared detection due to the narrowed band gap and good charge transport properties.A high photosensitivity of 1.8×10^(4),the ultrahigh photoresponsivity of 2,923 A W-1and the high detectivity of 4.26×10^(11)Jones of the organic near-infrared phototransistors are obtained.展开更多
Organic single crystals(OSCs)offer a unique combination of both individual and collective properties of the employed molecules,but it remains highly challenging to achieve OSCs with both high mobilities and strong flu...Organic single crystals(OSCs)offer a unique combination of both individual and collective properties of the employed molecules,but it remains highly challenging to achieve OSCs with both high mobilities and strong fluorescence emissions for their potential applications in multifunctional optoelectronics.Herein,we demonstrate the design and synthesis of two novel triphenylamine-functionalized thienoacenes-based organic semiconductors,4,8-distriphenylamineethynylbenzo[1,2-b:4,5-b′]dithiophene(4,8-DTEBDT)and 2,6-distriphenylamineethynylbenzo[1,2-b:4,5-b′]dithiophene(2,6-DTEBDT),with high-mobility and strong fluorescence emission.The two compounds show the maximum mobilities up to 0.25 and 0.06 cm^(2) V^(-1) s^(-1),the photoluminescence quantum yields(PLQYs)of 51% and 45%,and the small binding energies down to 55.13 and 58.79 meV.The excellent electrical and optical properties ensured the application of 4,8-DTEBDT and 2,6-DTEBDT single crystals in ultrasensitive UV phototransistors,achieving high photoresponsivity of 9.60×105 and 6.43×10^(4) AW^(-1),and detectivity exceeding 5.68×10^(17) and 2.99×10^(16) Jones.展开更多
In the field of organic phototransistor, achieving both broad-spectral and high photosensitivity has always been a big challenge. The innovation of device structure has previously proven to be a possible solution to t...In the field of organic phototransistor, achieving both broad-spectral and high photosensitivity has always been a big challenge. The innovation of device structure has previously proven to be a possible solution to this problem. Here in this study, a novel organic phototransistor based on a high mobility n-type small molecule as the conducting layer and an isolated bulk heterojunction light-absorbing layer as the floating gate has been demonstrated in this study. With the special designed device structure, the phototransistor shows extremely high sensitivity to broad spectral and weak light irradiation, and the photoresponsivity and photocurrent/dark-current ratio of the device can reach up to 4840 mA/W and 1.8×10~5 respectively.For conclusion, this study suggests a potential way to obtain high-performance phototransistors at room temperature, which will further promote the commercial application of organic phototransistors.展开更多
Molybdenum ditelluride （MoTe2） has been demonstrated great potential in electronic and optoelectronic applications. However, the reported effective hole mobility remains far below its theoretical value. Herein, taki...Molybdenum ditelluride （MoTe2） has been demonstrated great potential in electronic and optoelectronic applications. However, the reported effective hole mobility remains far below its theoretical value. Herein, taking advantage of high-κ screening effect, we have fabricated back-gated MoTe2 transistors on an Al2O3 high-κ dielectric and systematically investigated the electronic and optoelectronic proper- ties. A high current on/off ratio exceeding 106 is achieved in the Al2O3-based MoTe2 transistors, and the hole mobility is demonstrated to be 150 cm2 V^-1 s^-1, compared to 0.2-20 cm^2 V^-1 s^-1 ever obtained from back-gated MoTe2 transistors in the literatures. Moreover, a considerable hole concentration of 1.2 × 10^13 cm 2 is attained in our Al2O3-based MoTe2 transistors owing to the strong gate control capa- bility, leading to a high on-state hole current of 6.1 μA μm^-1. After optimization, our Al2O3-based MoTe2 phototransistor exhibits outstanding photodetective performance, with a high responsivity of 543 AW^-1 and a high photogain of 1,662 at 405 nm light illumination, which are boosted around 419 times compared to the referential SiO2-based control devices. The mechanisms of photoconductivity in the Al2O3-based MoTe2 phototransistors have been analyzed in detail, and the photogating effect is considered to play an important role. This work may provide useful insight to improve carrier mobility in two-dimensional layered semiconductors and open opportunities to facilitate the development of high-performance photodetectors in the future.展开更多
Photogating and electrical gating are key physical mechanisms in organic phototransistors(OPTs).However,most OPTs are based on thick and polycrystalline films,which leads to substantially low efficiency of both photog...Photogating and electrical gating are key physical mechanisms in organic phototransistors(OPTs).However,most OPTs are based on thick and polycrystalline films,which leads to substantially low efficiency of both photogating and electrical gating and thus reduced photoresponse.Herein,high-performance OPTs based on few-layered organic single-crystalline heterojunctions are proposed and the obstacle of thick and polycrystalline films for photodetection is overcome.Because of the molecular scale thickness of the type I organic single-crystalline heterojunctions in OPTs,both photogating and electrical gating are highly efficient.By synergy of efficient photogating and electrical gating,key figures of merit of OPTs reach the highest among those based on planar heterojunctions so far as we know.The production of few-layered organic single-crystalline heterojunctions will provide a new type of advanced materials for various applications.展开更多
Organic phototransistors(OPTs),compared to traditional inorganic counterparts,have attracted a great deal of interest because of their inherent flexibility,light-weight,easy and low-cost fabrication,and are considered...Organic phototransistors(OPTs),compared to traditional inorganic counterparts,have attracted a great deal of interest because of their inherent flexibility,light-weight,easy and low-cost fabrication,and are considered as potential candidates for next-generation wearable electronics.Currently,significant advances have been made in OPTs with the development of new organic semiconductors and optimization of device fabrication protocols.Among various types of OPTs,small molecule organic single crystal phototransistors(OSCPTs)standout because of their exciting features,such as long exciton diffusion length and high charge carrier mobility relative to organic thinfilm phototransistors.In this review,a brief introduction to device architectures,working mechanisms and figure of merits for OPTs is presented.We then overview recent approaches employed and achievements made for the development of OSCPTs.Finally,we spotlight potential future directions to tackle the existing challenges in this field and accelerate the advancement of OSCPTs towards practical applications.展开更多
Organic phototransistors （OPTs） have been intensively studied in recent years due to the combined ad- vantages of phototransistors and organic semiconductors （OSCs）. However, the electrical performance of OPTs is ...Organic phototransistors （OPTs） have been intensively studied in recent years due to the combined ad- vantages of phototransistors and organic semiconductors （OSCs）. However, the electrical performance of OPTs is lar- gely limited by OSCs themselves, posing a challenge to further improve the performance of the devices. Preparing nano/mi- cro-structures of OSCs is considered as an effective way to improve the performance of OPTs. Polystyrene （PS） micro- sphere, as a kind of insulating and low-cost material, is ex- tensively used in fabricating nano/microporous structures, and the resulting devices exhibit high response to external stimuli. Therefore, we combined PS microspheres with OSCs to fabricate PS/OSC OPTs, and the Ilight/Idark ratio was en- hanced by two orders of magnitude compared with the pris- tine counterparts, which can be modulated from 46 to 1800 by controlling the diameters of PS microsphereso This strategy paves a way for developing high-performance OPTs with nano/microporous structures with potential applications in organic optoelectronics.展开更多
With both light detection and intrinsic amplification functions,organic phototransistors have demonstrated promising applications,including photodetection and photomemory.To achieve excellent photoresponse and superio...With both light detection and intrinsic amplification functions,organic phototransistors have demonstrated promising applications,including photodetection and photomemory.To achieve excellent photoresponse and superior photogain,a common and effective strategy is to modulate the trapping effect with the purpose of reducing recombination or prolonging the lifetime of the photogenerated charge carriers.However,introducing trapping sites delicately is challenging and might sacrifice the response rate together with a typical persistent photoconductivity.Here,we demonstrate a facile strategy for achieving high photo-responsive organic phototransistors with both persistent and switchable photoconductivity features via interface terminal group regulation.By varying the terminate groups of self-assembled monolayer(SAMs)from the strong electron withdrawing group-F,neutral−CH_(3) to electron donating−NH_(2) on the dielectric surface,we realize both minority carrier trapping and majority carrier trapping in the organic phototransistor based on the C8-BTBT active layer.The electron withdrawing effect of F significantly enhances the minority carrier trapping process and yields a high photoresponsivity with a long-lasting persistent photoconductivity.In contrast,the electron donating group−NH_(2) with a distinct majority carrier trapping ability causes switchable photoconductivity so that the photocurrent can rise pronouncedly and fully decay along with light on/off.Attractively,both cases can deliver high performance with photoresponsivities higher than 104 A W^(−1) together with a photosensitivity in the level of 107 and a detectivity of approximately 10^(15)–10^(16) Jones.Such a tunable,excellent photoresponse property enables the convenient exploration of organic phototransistors to satisfy different application requirements.展开更多
The fabrication and characterization of a Schottky-emitter heterojunction-collector UV-enhanced bipolar phototransistor （SHBT） are presented. The luminescence peak of the ZnO film is observed at 371nm in the PL spec...The fabrication and characterization of a Schottky-emitter heterojunction-collector UV-enhanced bipolar phototransistor （SHBT） are presented. The luminescence peak of the ZnO film is observed at 371nm in the PL spectrum. The sensitivity of the ultraviolet response from 200 to 400nm is enhanced noticeably, and the spectrum response at wavelengths longer than 400nm is also retained, The experiments show that the Au/n-ZnO/p-Si SHBT UV enhanced phototransistor enhances the sensitivity of the ultraviolet response noticeably. The UV response sensitivity at 370nm of the phototransistor is 5-10 times that of a ZnO/Si heterojunction UV enhanced photodiode.展开更多
We report our results on the modeling of the spectral response of the near-infrared（NIR） lattice-matched p-n-p In_（0.53）Ga_（0.47）As/InP heterojunction pbototransistors（HPTs）.The spectral response model is deve...We report our results on the modeling of the spectral response of the near-infrared（NIR） lattice-matched p-n-p In_（0.53）Ga_（0.47）As/InP heterojunction pbototransistors（HPTs）.The spectral response model is developed from the solution of the steady state continuity equations that dominate the excess optically generated minority-carriers in the active regions of the HPTs with accurate boundary-conditions.In addition,a detailed optical-power absorption profile is constructed for the device modeling.The calculated responsivity is in good agreement with the measured one for the incident radiation at980 nm,1310 nm,and 1550 nm.Furthermore,the variation in the responsivity of the device with the base region width is analyzed.展开更多
The outstanding performances of nanostructured allinorganic CsPbX_3(X = I, Br, Cl) perovskites in optoelectronic applications can be attributed to their unique combination of a suitable bandgap, high absorption coeffi...The outstanding performances of nanostructured allinorganic CsPbX_3(X = I, Br, Cl) perovskites in optoelectronic applications can be attributed to their unique combination of a suitable bandgap, high absorption coefficient, and long carrier lifetime, which are desirable for photodetectors. However, the photosensing performances of the CsPbI_3 nanomaterials are limited by their low charge-transport efficiency. In this study, a phototransistor with a bilayer structure of an organic semiconductor layer of 2,7-dioctyl [1] benzothieno[3,2-b] [1] benzothiophene and CsPbI_3 nanorod layer was fabricated. The high-quality CsPbI_3 nanorod layer obtained using a simple dip-coating method provided decent transistor performance of the hybrid transistor device.The perovskite layer efficiently absorbs light, while the organicsemiconductor layer acts as a transport channel for injected photogenerated carriers and provides gate modulation. The hybrid phototransistor exhibits high performance owing to the synergistic function of the photogating effect and field effect in the transistor,with a photoresponsivity as high as 4300 A W^(-1), ultra-high photosensitivity of 2.2 9 106, and excellent stability over 1 month.This study provides a strategy to combine the advantages of perovskite nanorods and organic semiconductors in fabrication of high-performance photodetectors.展开更多
During the past decades,transition metal dichalcogenides(TMDs) have received special focus for their unique properties in photoelectric detection.As one important member of TMDs,MoS2 has been made into photodetector p...During the past decades,transition metal dichalcogenides(TMDs) have received special focus for their unique properties in photoelectric detection.As one important member of TMDs,MoS2 has been made into photodetector purely or combined with other materials,such as graphene,ionic liquid,and ferroelectric materials.Here,we report a gate-free MoS2 phototransistor combined with organic ferroelectric material poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)).In this device,the remnant polarization field in P(VDF-TrFE) is obtained from the piezoelectric force microscope(PFM) probe with a positive or negative bias,which can turn the dipoles from disorder to be the same direction.Then,the MoS2 channel can be maintained at an accumulated state with downward polarization field modulation and a depleted state with upward polarization field modulation.Moreover,the P(VDF-TrFE) segregates MoS2 from oxygen and water molecules around surroundings,which enables a cleaner surface state.As a photodetector,an ultra-low dark current of 10^–11 A,on/off ration of more than 10^4 and a fast photoresponse time of 120 μs are achieved.This work provides a new method to make high-performance phototransistors assisted by the ferroelectric domain which can operate without a gate electrode and demonstrates great potential for ultra-low power consumption applications.展开更多
Polymer thin-film transistors （PTFTs） based on poly（3-hexylthiophene） are fabricated by the spin-coating process, and their photo-sensing characteristics are investigated under steady-state visible-light illuminat...Polymer thin-film transistors （PTFTs） based on poly（3-hexylthiophene） are fabricated by the spin-coating process, and their photo-sensing characteristics are investigated under steady-state visible-light illumination. The photosensitivity of the device is strongly modulated by gate voltage under various illuminations. When the device is in the subthreshold operating mode, a significant increase in its drain current is observed with a maximum photosensitivity of 1.7×10^3 at an illumination intensity of 1200 lx, and even with a relatively high photosensitivity of 611 at a low illumination intensity of 100 lx. However, when the device is in the on-state operating mode, the photosensitivity is very low： only 1.88 at an illumination intensity of 1200 lx for a gate voltage of -20 V and a drain voltage of -20 V. The results indicate that the devices could be used as photo-detectors or sensors in the range of visible light. The modulation mechanism of the photosensitivity in the PTFT is discussed in detail.展开更多
In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is ...In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is illustrated in detail. Different results under electrical bias, optical bias or combined electrical and optical bias are analyzed for an excellent UTC-DHPT performance. The results show that when the UTC-DHPT operates at three-terminal （3T） working mode with combined electrical bias and optical bias in base, it keeps a high optical responsivity of 34.72 A/W and the highest optical transition frequency of 120 GHz. The current gain of the 3T UTC-DHPT under 1.55-μm light illuminations reaches 62 dB. This indicates that the combined base electrical bias and optical bias of 3T UTC-DHPT can make sure that the UTC-DHPT provides high optical current gain and high optical transition frequency simultaneously.展开更多
Van der Waals heterostructures based on the two-dimensional(2D)semiconductor materials have attracted increasing attention due to their attractive properties.In this work,we demonstrate a high-sensitive back-gated pho...Van der Waals heterostructures based on the two-dimensional(2D)semiconductor materials have attracted increasing attention due to their attractive properties.In this work,we demonstrate a high-sensitive back-gated phototransistor based on the vertical HfSe_(2)/MoS_(2)heterostructure with a broad-spectral response from near-ultraviolet to near-infrared and an efficient gate tunability for photoresponse.Under bias,the phototransistor exhibits high responsivity of up to 1.42×103A/W,and ultrahigh specific detectivity of up to 1.39×1015cm·Hz^(1/2)·W^(-1).Moreover,it can also operate under zero bias with remarkable responsivity of 10.2 A/W,relatively high specific detectivity of 1.43×1014cm·Hz^(1/2)·W^(-1),ultralow dark current of 1.22 f A,and high on/off ratio of above 105.These results should be attributed to the fact that the vertical HfSe_(2)/MoS_(2)heterostructure not only improves the broadband photoresponse of the phototransistor but also greatly enhances its sensitivity.Therefore,the heterostructure provides a promising candidate for next generation high performance phototransistors.展开更多
Layered ReS_(2) with direct bandgap and strong in-plane anisotropy shows great potential to develop high-performance angle-resolved photodetectors and optoelectronic devices.However,systematic characterizations of the...Layered ReS_(2) with direct bandgap and strong in-plane anisotropy shows great potential to develop high-performance angle-resolved photodetectors and optoelectronic devices.However,systematic characterizations of the angle-dependent photoresponse of ReS_(2) are still very limited.Here,we studied the anisotropic photoresponse of layered ReS_(2) phototransistors in depth.Angel-resolved Raman spectrum and field-effect mobility are tested to confirm the inconsistency between its electrical and optical anisotropies,which are along 120°and 90°,respectively.We further measured the angle-resolved photoresponse of a ReS_(2) transistor with 6 diagonally paired electrodes.The maximum photoresponsivity exceeds 0.515 A·W^(-1) along b-axis,which is around 3.8 times larger than that along the direction perpendicular to b axis,which is consistent with the optical anisotropic directions.The incident wavelength-and power-dependent photoresponse measurement along two anisotropic axes further demonstrates that b axis has stronger light-ReS_(2) interaction,which explains the anisotropic photoresponse.We also observed angle-dependent photoresistive switching behavior of the ReS_(2) transistor,which leads to the formation of angle-resolved phototransistor memory.It has simplified structure to create dynamic optoelectronic resistive random access memory controlled spatially through polarized light.This capability has great potential for real-time pattern recognition and photoconfiguration of artificial neural networks(ANN)in a wide spectral range of sensitivity provided by polarized light.展开更多
Organic lead halide compounds with perovskite structure become a promising photovoltaic material for low- cost thin film solar cells in recent years. The property of perovskite/metal interface is a fundamental topic f...Organic lead halide compounds with perovskite structure become a promising photovoltaic material for low- cost thin film solar cells in recent years. The property of perovskite/metal interface is a fundamental topic for the effective charge transfer at metal electrodes. In this work, we develop an interface modification method of lithium bis（trifluoromethane sulfonimide） （LiTFSI） solution treatment, which can effectively decrease the charge transfer resistance at the CH3NHaPbI3_xClx/Au interface. After the solution treatment, uniform nan- odots are formed at the surface of CHaNH3PbI3_xCIx films, and the barrier height at CH3NH3PbI3_xCIx/Au interface reduces from 0.51 V to 0.08 V. As a consequence, the efficiency of hole conductor free solar cells with CH3NHaPbI3-xCIx harvester increase from 4.0% to 7.6% under one sun condition. It is also found that the hole conductor free perovskite solar cell can work in a photodetector mode, which has the same output prop- erties with phototransistors. After the LiTFSI solution treatment, the sensitivity of this photodetector can be improved for about one time.展开更多
基金supported by Grants from the UK EPSRC Future Compound Semiconductor Manufacturing Hub(EP/P006973/1)the financial support from EPSRC(EP/L018330/1,EP/N032888/1)+3 种基金the U.S.Army Research Laboratory under Cooperative Agreement Number W911NF-16-2-0120the “973 Program—the National Basic Research Program of China” Special Funds for the Chief Young Scientis(2015CB358600)the Excellent Young Scholar Fund from National Natural Science Foundation of China(21422103)the China Scholarship Council(CSC)
文摘Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2(1−x)Se2x alloys,synthesized by a simple and controllable chemical solution deposition method,are reported.The graded bandgaps,arising from the spatial grading of Se composition and thickness within a single domain,are tuned from 1.83 to 1.73 eV,leading to the formation of a homojunction with a builtin electric field.Consequently,a strong and sensitive gate-modulated photovoltaic effect is demonstrated,enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 mA W−1,a specific detectivity up to^10^11 Jones,and an on/off ratio up to^10^4.Remarkably,when illuminated by the lights ranging from 405 to 808 nm,the biased devices yield a champion photoresponsivity of 191.5 A W−1,a specific detectivity up to^1012 Jones,a photoconductive gain of 10^6–10^7,and a photoresponsive time in the order of^50 ms.These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions.
基金This work is supported by National Natural Science Foundation of China(No.92163135,11904098,51972105,U19A2090 and 62090035)Hunan Provincial Natural Science Foundation of China(No.2019JJ30004)+1 种基金Hunan International Innovation Cooperation Platform(No.2018WK4004)Key Program of Science and Technology Department of Hunan Province(Nos.2019XK2001,2020XK2001).
文摘Mix-dimensional van der Waals heterostructures(vdWHs)have inspired worldwide interests and efforts in the field of ad-vanced electronics and optoelectronics.The fundamental understanding of interfacial charge transfer is of vital import-ance for guiding the design of functional optoelectronic applications.In this work,type-Ⅱ0D-2D CdSe/ZnS quantum dots/MoS_(2)vdWHs are designed to study the light-triggered interfacial charge behaviors and enhanced optoelectronic performances.From spectral measurements in both steady and transient states,the phenomena of suppressed photolu-minescence(PL)emissions,shifted Raman signals and changed PL lifetimes provide strong evidences of efficient charge transfer at the 0D-2D interface.A series of spectral evolutions of heterostructures with various QDs overlapping concentrations at different laser powers are analyzed in details,which clarifies the dynamic competition between exciton and trion during an efficient doping of 3.9×10^(13)cm^(−2).The enhanced photoresponses(1.57×10^(4)A·W^(-1))and detectivities(2.86×10^(11)Jones)in 0D/2D phototransistors further demonstrate that the light-induced charge transfer is still a feasible way to optimize the performance of optoelectronic devices.These results are expected to inspire the basic understand-ing of interfacial physics at 0D/2D interfaces,and shed the light on promoting the development of mixed-dimensional op-toelectronic devices in the near future.
基金N.R.P.acknowledged NSF-PREM through NSFDMR-1826886,HBCU-UP Excellence in research NSFDMR-1900692A portion of this work was performed at the National High Magnetic Field Laboratory,which is supported by the National Science Foundation Cooperative Agreement No.DMR-1644779+1 种基金the State of Florida.This work was performed,in part,at the Center for Nanoscale Materials,a U.S.Department of Energy Office of Science User Facilitysupported by the U.S.Department of Energy,Office of Science,under Contract No.DE-AC02-06CH11357.
文摘We report intrinsic photoconductivity studies on one of the least examined layered compounds,ZrS2.Few-atomic layer ZrS2 field-effect transistors were fabricated on the Si/SiO2 substrate and photoconductivity measurements were performed using both two-and four-terminal configurations under the illumination of 532 nm laser source.We measured photocurrent as a function of the incident optical power at several source-drain(bias)voltages.We observe a significantly large photoconductivity when measured in the multiterminal(four-terminal)configuration compared to that in the two-terminal configuration.For an incident optical power of 90 nW,the estimated photosensitivity and the external quantum efficiency(EQE)measured in two-terminal configuration are 0.5 A/W and 120%,respectively,under a bias voltage of 650 mV.Under the same conditions,the four-terminal measurements result in much higher values for both the photoresponsivity(R)and EQE to 6 A/W and 1400%,respectively.This significant improvement in photoresponsivity and EQE in the four-terminal configuration may have been influenced by the reduction of contact resistance at the metal-semiconductor interface,which greatly impacts the carrier mobility of low conducting materials.This suggests that photoconductivity measurements performed through the two-terminal configuration in previous studies on ZrS2 and other 2D materials have severely underestimated the true intrinsic properties of transition metal dichalcogenides and their remarkable potential for optoelectronic applications.
基金supported by the Ministry of Science and Technology of China(2018YFA0703200 and 2017YFA0204503)the National Natural Science Foundation of China(52121002,51733004,U21A6002,51725304 and 21875158)+1 种基金Tianjin Natural Science Foundation(20JCJQJC00300)China Postdoctoral Science Foundation(2021M692381)。
文摘Near-infrared organic phototransistors have wide application prospects in many fields.The active materials with the high mobility and near-infrared response are critical to building high-performance near-infrared organic phototransistors,which are scarce at present.Herein,a new charge transfer cocrystal using 5,7-dihydroindolo[2,3-b]carbazole(5,7-ICZ)as the donor and 2,2’-(benzo[1,2-b:4,5-b’]dithiophene-4,8-diylidene)dimalononitrile(DTTCNQ)as the acceptor is properly designed and prepared in a stoichiometric ratio(D:A=1:1),which not only displays a high electron mobility of 0.15 cm^(2)V^(-1)s^(-1) and very low dark current,but also can serve as the active layer materials in the region of near-infrared detection due to the narrowed band gap and good charge transport properties.A high photosensitivity of 1.8×10^(4),the ultrahigh photoresponsivity of 2,923 A W-1and the high detectivity of 4.26×10^(11)Jones of the organic near-infrared phototransistors are obtained.
文摘Organic single crystals(OSCs)offer a unique combination of both individual and collective properties of the employed molecules,but it remains highly challenging to achieve OSCs with both high mobilities and strong fluorescence emissions for their potential applications in multifunctional optoelectronics.Herein,we demonstrate the design and synthesis of two novel triphenylamine-functionalized thienoacenes-based organic semiconductors,4,8-distriphenylamineethynylbenzo[1,2-b:4,5-b′]dithiophene(4,8-DTEBDT)and 2,6-distriphenylamineethynylbenzo[1,2-b:4,5-b′]dithiophene(2,6-DTEBDT),with high-mobility and strong fluorescence emission.The two compounds show the maximum mobilities up to 0.25 and 0.06 cm^(2) V^(-1) s^(-1),the photoluminescence quantum yields(PLQYs)of 51% and 45%,and the small binding energies down to 55.13 and 58.79 meV.The excellent electrical and optical properties ensured the application of 4,8-DTEBDT and 2,6-DTEBDT single crystals in ultrasensitive UV phototransistors,achieving high photoresponsivity of 9.60×105 and 6.43×10^(4) AW^(-1),and detectivity exceeding 5.68×10^(17) and 2.99×10^(16) Jones.
基金supported financially by the Ministry of Science and Technology of the People's Republic of China(No.2017YFA0206600)the National Natural Science Foundation of China(Nos.52050171,51822301,22175047,52103203,and 91963126)+4 种基金the CAS Instrument Development Project(No.YJKYYQ20170037)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB36020000)the CAS Pioneer Hundred Talents Programthe Natural Science Foundation of Shandong Province(No.ZR2020ME070)China Postdoctoral Science Foundation(No.2021M690802)。
文摘In the field of organic phototransistor, achieving both broad-spectral and high photosensitivity has always been a big challenge. The innovation of device structure has previously proven to be a possible solution to this problem. Here in this study, a novel organic phototransistor based on a high mobility n-type small molecule as the conducting layer and an isolated bulk heterojunction light-absorbing layer as the floating gate has been demonstrated in this study. With the special designed device structure, the phototransistor shows extremely high sensitivity to broad spectral and weak light irradiation, and the photoresponsivity and photocurrent/dark-current ratio of the device can reach up to 4840 mA/W and 1.8×10~5 respectively.For conclusion, this study suggests a potential way to obtain high-performance phototransistors at room temperature, which will further promote the commercial application of organic phototransistors.
基金supported by the National Key Research and Development Program of China(2016YFA0302300,016YFA0200400)the National Science and Technology Major Project of China(2016ZX02301001)+1 种基金the National Natural Science Foundation of China(61306105)the Tsinghua University Initiative Scientific Research Program
文摘Molybdenum ditelluride （MoTe2） has been demonstrated great potential in electronic and optoelectronic applications. However, the reported effective hole mobility remains far below its theoretical value. Herein, taking advantage of high-κ screening effect, we have fabricated back-gated MoTe2 transistors on an Al2O3 high-κ dielectric and systematically investigated the electronic and optoelectronic proper- ties. A high current on/off ratio exceeding 106 is achieved in the Al2O3-based MoTe2 transistors, and the hole mobility is demonstrated to be 150 cm2 V^-1 s^-1, compared to 0.2-20 cm^2 V^-1 s^-1 ever obtained from back-gated MoTe2 transistors in the literatures. Moreover, a considerable hole concentration of 1.2 × 10^13 cm 2 is attained in our Al2O3-based MoTe2 transistors owing to the strong gate control capa- bility, leading to a high on-state hole current of 6.1 μA μm^-1. After optimization, our Al2O3-based MoTe2 phototransistor exhibits outstanding photodetective performance, with a high responsivity of 543 AW^-1 and a high photogain of 1,662 at 405 nm light illumination, which are boosted around 419 times compared to the referential SiO2-based control devices. The mechanisms of photoconductivity in the Al2O3-based MoTe2 phototransistors have been analyzed in detail, and the photogating effect is considered to play an important role. This work may provide useful insight to improve carrier mobility in two-dimensional layered semiconductors and open opportunities to facilitate the development of high-performance photodetectors in the future.
基金the National Natural Science Foundation of China(Nos.51873148,52073206,51633006,and 61704038)the Natural Science Foundation of Tianjin City(No.18JC-YBJC18400)Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000).
文摘Photogating and electrical gating are key physical mechanisms in organic phototransistors(OPTs).However,most OPTs are based on thick and polycrystalline films,which leads to substantially low efficiency of both photogating and electrical gating and thus reduced photoresponse.Herein,high-performance OPTs based on few-layered organic single-crystalline heterojunctions are proposed and the obstacle of thick and polycrystalline films for photodetection is overcome.Because of the molecular scale thickness of the type I organic single-crystalline heterojunctions in OPTs,both photogating and electrical gating are highly efficient.By synergy of efficient photogating and electrical gating,key figures of merit of OPTs reach the highest among those based on planar heterojunctions so far as we know.The production of few-layered organic single-crystalline heterojunctions will provide a new type of advanced materials for various applications.
基金the Key-Area Research and Development Program of Guangdong Province(No.2019B010924003)Guangdong Basic and Applied Basic Research Foundation(No.2020B1515120030)+5 种基金the Shenzhen Peacock Plan(No.KQTD2014062714543296)the Shenzhen Science and Technology Research Grant(No.JCYJ20180302153514509)the Guangdong International Science Collaboration Base(No.2019A050505003)the Shenzhen Engineering Research Center(Shenzhen Development and Reform Commission[2018]1410)the Shenzhen Key Laboratory of Organic Optoelectromagnetic Functional Materials(No.ZDSYS20140509094114164)the Natural Science Basic Research Program of Shaanxi(Program No.2019JLP11).
文摘Organic phototransistors(OPTs),compared to traditional inorganic counterparts,have attracted a great deal of interest because of their inherent flexibility,light-weight,easy and low-cost fabrication,and are considered as potential candidates for next-generation wearable electronics.Currently,significant advances have been made in OPTs with the development of new organic semiconductors and optimization of device fabrication protocols.Among various types of OPTs,small molecule organic single crystal phototransistors(OSCPTs)standout because of their exciting features,such as long exciton diffusion length and high charge carrier mobility relative to organic thinfilm phototransistors.In this review,a brief introduction to device architectures,working mechanisms and figure of merits for OPTs is presented.We then overview recent approaches employed and achievements made for the development of OSCPTs.Finally,we spotlight potential future directions to tackle the existing challenges in this field and accelerate the advancement of OSCPTs towards practical applications.
基金supported by the National Natural Science Foundation of China (51741302, 51603151 and 51373123)the National Key Research and Development Program of China (2017YFA0103900 and 2017YFA0103904)+1 种基金Science and Technology Foundation of Shanghai (17JC1404600)the Fundamental Research Funds for the Central Universities
文摘Organic phototransistors （OPTs） have been intensively studied in recent years due to the combined ad- vantages of phototransistors and organic semiconductors （OSCs）. However, the electrical performance of OPTs is lar- gely limited by OSCs themselves, posing a challenge to further improve the performance of the devices. Preparing nano/mi- cro-structures of OSCs is considered as an effective way to improve the performance of OPTs. Polystyrene （PS） micro- sphere, as a kind of insulating and low-cost material, is ex- tensively used in fabricating nano/microporous structures, and the resulting devices exhibit high response to external stimuli. Therefore, we combined PS microspheres with OSCs to fabricate PS/OSC OPTs, and the Ilight/Idark ratio was en- hanced by two orders of magnitude compared with the pris- tine counterparts, which can be modulated from 46 to 1800 by controlling the diameters of PS microsphereso This strategy paves a way for developing high-performance OPTs with nano/microporous structures with potential applications in organic optoelectronics.
基金supported by the National Key Research and Development Program of China (2018YFE0200700)the National Natural Science Foundation of China (52173176,51773143,51821002)+2 种基金the Collaborative Innovation Center of Suzhou Nano Science&Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the 111 Project
文摘With both light detection and intrinsic amplification functions,organic phototransistors have demonstrated promising applications,including photodetection and photomemory.To achieve excellent photoresponse and superior photogain,a common and effective strategy is to modulate the trapping effect with the purpose of reducing recombination or prolonging the lifetime of the photogenerated charge carriers.However,introducing trapping sites delicately is challenging and might sacrifice the response rate together with a typical persistent photoconductivity.Here,we demonstrate a facile strategy for achieving high photo-responsive organic phototransistors with both persistent and switchable photoconductivity features via interface terminal group regulation.By varying the terminate groups of self-assembled monolayer(SAMs)from the strong electron withdrawing group-F,neutral−CH_(3) to electron donating−NH_(2) on the dielectric surface,we realize both minority carrier trapping and majority carrier trapping in the organic phototransistor based on the C8-BTBT active layer.The electron withdrawing effect of F significantly enhances the minority carrier trapping process and yields a high photoresponsivity with a long-lasting persistent photoconductivity.In contrast,the electron donating group−NH_(2) with a distinct majority carrier trapping ability causes switchable photoconductivity so that the photocurrent can rise pronouncedly and fully decay along with light on/off.Attractively,both cases can deliver high performance with photoresponsivities higher than 104 A W^(−1) together with a photosensitivity in the level of 107 and a detectivity of approximately 10^(15)–10^(16) Jones.Such a tunable,excellent photoresponse property enables the convenient exploration of organic phototransistors to satisfy different application requirements.
文摘The fabrication and characterization of a Schottky-emitter heterojunction-collector UV-enhanced bipolar phototransistor （SHBT） are presented. The luminescence peak of the ZnO film is observed at 371nm in the PL spectrum. The sensitivity of the ultraviolet response from 200 to 400nm is enhanced noticeably, and the spectrum response at wavelengths longer than 400nm is also retained, The experiments show that the Au/n-ZnO/p-Si SHBT UV enhanced phototransistor enhances the sensitivity of the ultraviolet response noticeably. The UV response sensitivity at 370nm of the phototransistor is 5-10 times that of a ZnO/Si heterojunction UV enhanced photodiode.
基金Project supported by the National Natural Science Foundation of China(Grant No.61307044)the National Basic Research Program of China(Grant No.2012CB619200)+4 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20130321)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20133201120009)the Open Project of Key Laboratory of Infrared Imaging Materials and Detectors,Chinese Academy of Sciences(IIMDKFJJ-15-06)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of Chinathe Research Innovation Program for College Graduates of Jiangsu Province,China(Grant No.SJLX15-0600)
文摘We report our results on the modeling of the spectral response of the near-infrared（NIR） lattice-matched p-n-p In_（0.53）Ga_（0.47）As/InP heterojunction pbototransistors（HPTs）.The spectral response model is developed from the solution of the steady state continuity equations that dominate the excess optically generated minority-carriers in the active regions of the HPTs with accurate boundary-conditions.In addition,a detailed optical-power absorption profile is constructed for the device modeling.The calculated responsivity is in good agreement with the measured one for the incident radiation at980 nm,1310 nm,and 1550 nm.Furthermore,the variation in the responsivity of the device with the base region width is analyzed.
基金supported by the National Key Research and Development Program of China (2017YFA0103904)the National Nature Science Foundation of China (51741302 and 51603151)+2 种基金Science & Technology Foundation of Shanghai (17JC1404600)the Fundamental Research Funds for the Central Universitiesthe support of College of Transportation Engineering,Tongji University’s Shanghai ‘‘Gaofeng’’ subject
文摘The outstanding performances of nanostructured allinorganic CsPbX_3(X = I, Br, Cl) perovskites in optoelectronic applications can be attributed to their unique combination of a suitable bandgap, high absorption coefficient, and long carrier lifetime, which are desirable for photodetectors. However, the photosensing performances of the CsPbI_3 nanomaterials are limited by their low charge-transport efficiency. In this study, a phototransistor with a bilayer structure of an organic semiconductor layer of 2,7-dioctyl [1] benzothieno[3,2-b] [1] benzothiophene and CsPbI_3 nanorod layer was fabricated. The high-quality CsPbI_3 nanorod layer obtained using a simple dip-coating method provided decent transistor performance of the hybrid transistor device.The perovskite layer efficiently absorbs light, while the organicsemiconductor layer acts as a transport channel for injected photogenerated carriers and provides gate modulation. The hybrid phototransistor exhibits high performance owing to the synergistic function of the photogating effect and field effect in the transistor,with a photoresponsivity as high as 4300 A W^(-1), ultra-high photosensitivity of 2.2 9 106, and excellent stability over 1 month.This study provides a strategy to combine the advantages of perovskite nanorods and organic semiconductors in fabrication of high-performance photodetectors.
基金supported by the Major State Basic Research Development Program (Grant Nos. 2016YFA0203900, 2016YFB0400801 and 2015CB921600)Key Research Project of Frontier Sciences of Chinese Academy of Sciences (Nos. QYZDB-SSW-JSC016, QYZDY-SSW-JSC042)+2 种基金Strategic Priority Research Program of Chinese Academy of Sciences (XDPB12, XDB 3000000)Natural Science Foundation of China (Grant Nos. 61521001, 61574151, 61574152, 61674158, 61722408, 61734003 and 61835012)Natural Science Foundation of Shanghai (Grant No. 16ZR1447600, 17JC1400302)
文摘During the past decades,transition metal dichalcogenides(TMDs) have received special focus for their unique properties in photoelectric detection.As one important member of TMDs,MoS2 has been made into photodetector purely or combined with other materials,such as graphene,ionic liquid,and ferroelectric materials.Here,we report a gate-free MoS2 phototransistor combined with organic ferroelectric material poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)).In this device,the remnant polarization field in P(VDF-TrFE) is obtained from the piezoelectric force microscope(PFM) probe with a positive or negative bias,which can turn the dipoles from disorder to be the same direction.Then,the MoS2 channel can be maintained at an accumulated state with downward polarization field modulation and a depleted state with upward polarization field modulation.Moreover,the P(VDF-TrFE) segregates MoS2 from oxygen and water molecules around surroundings,which enables a cleaner surface state.As a photodetector,an ultra-low dark current of 10^–11 A,on/off ration of more than 10^4 and a fast photoresponse time of 120 μs are achieved.This work provides a new method to make high-performance phototransistors assisted by the ferroelectric domain which can operate without a gate electrode and demonstrates great potential for ultra-low power consumption applications.
基金Projected supported by the National Natural Science Foundation of China (Grant No. 61076113)the Natural Science Foundation of Guangdong Province,China (Grant No. 8451064101000257)the Research Grants Council (RGC) of Hong Kong Special Administrative Region (HKSAR),China (Grant No. HKU 7133/07E)
文摘Polymer thin-film transistors （PTFTs） based on poly（3-hexylthiophene） are fabricated by the spin-coating process, and their photo-sensing characteristics are investigated under steady-state visible-light illumination. The photosensitivity of the device is strongly modulated by gate voltage under various illuminations. When the device is in the subthreshold operating mode, a significant increase in its drain current is observed with a maximum photosensitivity of 1.7×10^3 at an illumination intensity of 1200 lx, and even with a relatively high photosensitivity of 611 at a low illumination intensity of 100 lx. However, when the device is in the on-state operating mode, the photosensitivity is very low： only 1.88 at an illumination intensity of 1200 lx for a gate voltage of -20 V and a drain voltage of -20 V. The results indicate that the devices could be used as photo-detectors or sensors in the range of visible light. The modulation mechanism of the photosensitivity in the PTFT is discussed in detail.
基金Project supported by the National Natural Science Foundation of China(Grant No.61006044)the Natural Science Foundation of Beijing,China(Grant Nos.4122014 and 4142007)the Fund from the Beijing Municipal Education Committee,China(Grant No.KM200910005001)
文摘In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is illustrated in detail. Different results under electrical bias, optical bias or combined electrical and optical bias are analyzed for an excellent UTC-DHPT performance. The results show that when the UTC-DHPT operates at three-terminal （3T） working mode with combined electrical bias and optical bias in base, it keeps a high optical responsivity of 34.72 A/W and the highest optical transition frequency of 120 GHz. The current gain of the 3T UTC-DHPT under 1.55-μm light illuminations reaches 62 dB. This indicates that the combined base electrical bias and optical bias of 3T UTC-DHPT can make sure that the UTC-DHPT provides high optical current gain and high optical transition frequency simultaneously.
基金Project supported by the National Natural Science Foundation of China(Grant No.51702245)the Fundamental Research Funds for the Central Universities(Grant No.WUT2021III065JC)
文摘Van der Waals heterostructures based on the two-dimensional(2D)semiconductor materials have attracted increasing attention due to their attractive properties.In this work,we demonstrate a high-sensitive back-gated phototransistor based on the vertical HfSe_(2)/MoS_(2)heterostructure with a broad-spectral response from near-ultraviolet to near-infrared and an efficient gate tunability for photoresponse.Under bias,the phototransistor exhibits high responsivity of up to 1.42×103A/W,and ultrahigh specific detectivity of up to 1.39×1015cm·Hz^(1/2)·W^(-1).Moreover,it can also operate under zero bias with remarkable responsivity of 10.2 A/W,relatively high specific detectivity of 1.43×1014cm·Hz^(1/2)·W^(-1),ultralow dark current of 1.22 f A,and high on/off ratio of above 105.These results should be attributed to the fact that the vertical HfSe_(2)/MoS_(2)heterostructure not only improves the broadband photoresponse of the phototransistor but also greatly enhances its sensitivity.Therefore,the heterostructure provides a promising candidate for next generation high performance phototransistors.
文摘Layered ReS_(2) with direct bandgap and strong in-plane anisotropy shows great potential to develop high-performance angle-resolved photodetectors and optoelectronic devices.However,systematic characterizations of the angle-dependent photoresponse of ReS_(2) are still very limited.Here,we studied the anisotropic photoresponse of layered ReS_(2) phototransistors in depth.Angel-resolved Raman spectrum and field-effect mobility are tested to confirm the inconsistency between its electrical and optical anisotropies,which are along 120°and 90°,respectively.We further measured the angle-resolved photoresponse of a ReS_(2) transistor with 6 diagonally paired electrodes.The maximum photoresponsivity exceeds 0.515 A·W^(-1) along b-axis,which is around 3.8 times larger than that along the direction perpendicular to b axis,which is consistent with the optical anisotropic directions.The incident wavelength-and power-dependent photoresponse measurement along two anisotropic axes further demonstrates that b axis has stronger light-ReS_(2) interaction,which explains the anisotropic photoresponse.We also observed angle-dependent photoresistive switching behavior of the ReS_(2) transistor,which leads to the formation of angle-resolved phototransistor memory.It has simplified structure to create dynamic optoelectronic resistive random access memory controlled spatially through polarized light.This capability has great potential for real-time pattern recognition and photoconfiguration of artificial neural networks(ANN)in a wide spectral range of sensitivity provided by polarized light.
基金supported by the National Natural Science Foundation of China (51273079,11404133)the Science Development Program of Jilin Province (20150519021JH)the Fundamental Research Funds for Central Universities at Jilin University
文摘Organic lead halide compounds with perovskite structure become a promising photovoltaic material for low- cost thin film solar cells in recent years. The property of perovskite/metal interface is a fundamental topic for the effective charge transfer at metal electrodes. In this work, we develop an interface modification method of lithium bis（trifluoromethane sulfonimide） （LiTFSI） solution treatment, which can effectively decrease the charge transfer resistance at the CH3NHaPbI3_xClx/Au interface. After the solution treatment, uniform nan- odots are formed at the surface of CHaNH3PbI3_xCIx films, and the barrier height at CH3NH3PbI3_xCIx/Au interface reduces from 0.51 V to 0.08 V. As a consequence, the efficiency of hole conductor free solar cells with CH3NHaPbI3-xCIx harvester increase from 4.0% to 7.6% under one sun condition. It is also found that the hole conductor free perovskite solar cell can work in a photodetector mode, which has the same output prop- erties with phototransistors. After the LiTFSI solution treatment, the sensitivity of this photodetector can be improved for about one time.
