The exploitation of fossil resources to meet humanity’s energy needs is the root cause of the climate warming phenomenon facing the planet. In this context, non-carbon-based energies, such as photovoltaic energy, are...The exploitation of fossil resources to meet humanity’s energy needs is the root cause of the climate warming phenomenon facing the planet. In this context, non-carbon-based energies, such as photovoltaic energy, are identified as crucial solutions. Organic perovskites MAPbI<sub>3</sub> and FAPbI<sub>3</sub>, characterized by their abundance, low cost, and ease of synthesis, are emerging as candidates for study to enhance their competitiveness. It is within this framework that this article presents a comparative analysis of the performances of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> perovskites in the context of photovoltaic devices. The analysis focuses on the optoelectronic characteristics and stability of these high-potential materials. The optical properties of perovskites are rigorously evaluated, including band gaps, photoluminescence, and light absorption, using UV-Vis spectroscopy and photoluminescence techniques. The crystal structure is characterized by X-ray diffraction, while film morphology is examined through scanning electron microscopy. The results reveal significant variations between the two types of perovskites, directly impacting the performance of resulting solar devices. Simultaneously, the stability of perovskites is subjected to a thorough study, exposing the materials to various environmental conditions, highlighting key determinants of their durability. Films of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> demonstrate distinct differences in terms of topography, optical performance, and stability. Research has unveiled that planar perovskite solar cells based on FAPbI<sub>3</sub> offer higher photoelectric conversion efficiency, surpassing their MAPbI<sub>3</sub>-based counterparts in terms of performance. These advancements aim to overcome stability constraints and enhance the long-term durability of perovskites, ultimately aiming for practical application of these materials. This comprehensive comparative analysis provides an enlightened understanding of the optoelectronic performance and stability of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> perovskites, which is critically important to guide future research and development of solar devices that are both more efficient and sustainable.展开更多
Al-doped ZnO thin films were prepared on glass substrate using an ultra-high density target by RF magnetron sputtering at room temperature. The microstructure, surface morphology, optical and electrical properties of ...Al-doped ZnO thin films were prepared on glass substrate using an ultra-high density target by RF magnetron sputtering at room temperature. The microstructure, surface morphology, optical and electrical properties of AZO thin films were investigated by X-ray diffractometer, scanning electron microscope, UV-visible spectrophotometer, four-point probe method, and Hall-effect measurement system. The results showed that all the films obtained were polycrystalline with a hexagonal structure and average optical transmittance of AZO thin films was over 85 % at different sputtering powers. The sputtering power had a great effect on optoelectronic properties of the AZO thin films, especially on the resistivity. The lowest resistivity of 4.5×10^-4 Ω·cm combined with the transmittance of 87.1% was obtained at sputtering power of 200 W. The optical band gap varied between 3.48 and 3.68 eV.展开更多
The perfluoroalkyl substances（PFS） have attracted considerable attention in recent years as a persistent global pollutant to be able to bioaccumulate in higher organisms.In this paper,theoretical analysis on electro...The perfluoroalkyl substances（PFS） have attracted considerable attention in recent years as a persistent global pollutant to be able to bioaccumulate in higher organisms.In this paper,theoretical analysis on electronic structures,optoelectronic properties and absorption spectra properties of the perflurooctane sulfonate（PFOS） in gas phase have been investigated by using the DFT/TD-DFT method.The geometric structures,electrostatic potentials,energy gaps,ionization potentials,electron affinities,frontier molecular orbital,excitation energies and absorption spectra for the ground state of PFOS were calculated.The result indicates that the ability of accepting electron of neutral PFOS is larger than that of anionic PFOS,while the electron excited by UV irradiation from HOMO to LUMO in the anionic PFOS is easier than that in the neutral PFOS.展开更多
Advanced GGA ＋ U（Hubbard） and modified Becke–Johnson（mBJ） techniques are used for the calculation of the structural, electronic, and optical parameters of α-Al2-x CoxO3（x = 0.0, 0.167） compounds. The direct b...Advanced GGA ＋ U（Hubbard） and modified Becke–Johnson（mBJ） techniques are used for the calculation of the structural, electronic, and optical parameters of α-Al2-x CoxO3（x = 0.0, 0.167） compounds. The direct band gaps calculated by GGA and m BJ for pure alumina are 6.3 eV and 8.5 eV, respectively. The m BJ approximation provides results very close to the experimental one（8.7 eV）. The substitution of Al with Co reduces the band gap of alumina. The wide and direct band gap of the doped alumina predicts that it can efficiently be used in optoelectronic devices. The optical properties of the compounds like dielectric functions and energy loss function are also calculated. The rhombohedral structure of theα-Al2-x CoxO3（x = 0.0, 0.167） compounds reveal the birefringence properties.展开更多
The effect of back-diffusion of Mg dopants on optoelectronic characteristics of InGaN-based green light-emitting diodes （LEDs） is investigated. The LEDs with less Mg back-diffusion show blue shifts of longer wavelen...The effect of back-diffusion of Mg dopants on optoelectronic characteristics of InGaN-based green light-emitting diodes （LEDs） is investigated. The LEDs with less Mg back-diffusion show blue shifts of longer wavelengths and larger wavelengths with the increasing current, which results from the Mg-dopant-related polarization screening. The LEDs show enhanced efficiency with the decreasing Mg back-diffusion in the lower current region. Light outputs follow the power law L α I^m, with smaller parameter m in the LEDs with less Mg back-diffusion, indicating a lower density of trap states. The trap-assisted tunneling current is also suppressed by reducing Mg- defect-related nonradiative centers in the active region. Furthermore, the forward current-voltage characteristics are improved.展开更多
Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augment...Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.展开更多
PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and ind...PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and indirect-to-direct gap transition under strain; however, these properties have not been verified experimentally. Here we report the first experimental exploration of its optoelectronic properties under external pressure. We find that the photocurrent is weakly pressuredependent below 3 GPa but increases significantly in the pressure range of 3 GPa–4 GPa, with a maximum ～ 6 times higher than that at ambient pressure. X-ray diffraction data shows that no structural phase transition can be observed up to26.8 GPa, which indicates a stable lattice structure of PtS2 under high pressure. This is further supported by our Raman measurements with an observation of linear blue-shifts of the two Raman-active modes to 6.4 GPa. The pressure-enhanced photocurrent is related to the indirect-to-direct/quasi-direct bandgap transition under pressure, resembling the gap behavior under compression strain as predicted theoretically.展开更多
This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal--semiconductor metal （MSM） structure by dieleetrophoresis and studying on its electrical ch...This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal--semiconductor metal （MSM） structure by dieleetrophoresis and studying on its electrical characteristics by using current-voltage （Ⅰ - Ⅴ） measurements. An electronic model with two back to back Sehottky diodes in series with a semiconductor of nanowires was established to study the electrical transport of the MSM structures. By fitting the measured Ⅰ - Ⅴ characteristics using the proposed model, the parameters of the Schottky contacts and the resistance of nanowires could be acquired. The photoelectric properties of the MSM structures were also investigated by analysing the measurements of the electrical transports under various light intensities. The deduced results demonstrate that ZnO nanowires and their Schottky contacts with Au electrodes both contribute to photosensitivity and the MSM structures with ZnO nanowires are potentially applicable for photonic devices.展开更多
While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remai...While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B_(2)S_(2) and Syn-B_(2)S_(2), as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10^(-3)cm^(2)V^(-1)s^(-1)were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.展开更多
The influence of substrate temperature and nozzle-to-substrate distance（NSD） on the structural,morphological, optical and electrical properties of Sb：SnO_2 thin films prepared by chemical spray pyrolysis has been a...The influence of substrate temperature and nozzle-to-substrate distance（NSD） on the structural,morphological, optical and electrical properties of Sb：SnO_2 thin films prepared by chemical spray pyrolysis has been analyzed.The structural,morphological,optical and electrical properties were characterized by using XRD,SEM, UV-visible spectrophotometry and Hall effect measurement techniques.It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the（200） reflection.The pyramidal crystallites formed due to coalescence were observed from SEM images.The values of highest conductivity,optical transmittance and figure of merit of about 1449（Ω·cm）^（-1）,70%and 5.2×10^（-3）□/Ω,respectively,were observed for a typical film deposited using optimal conditions（substrate temperature = 500℃and NSD = 30 cm）.展开更多
SnSe thin films of thickness 180 nm have been deposited on glass substrates by reactive evaporation at an optimized substrate temperature of 523 ± 5 K and pressure of 10^（-5） mbar.The as-prepared SnSe thin film...SnSe thin films of thickness 180 nm have been deposited on glass substrates by reactive evaporation at an optimized substrate temperature of 523 ± 5 K and pressure of 10^（-5） mbar.The as-prepared SnSe thin films are characterized for their structural,optical and electrical properties by various experimental techniques.The p-type conductivity,near-optimum direct band gap,high absorption coefficient and good photosensitivity of the SnSe thin film indicate its suitability for photovoltaic applications.The optical constants,loss factor,quality factor and optical conductivity of the films are evaluated.The results of Hall and thermoelectric power measurements are correlated to determine the density of states,Fermi energy and effective mass of carriers and are obtained as 2.8×10^（17）cm^（-3）,0.03 eV and 0.05m_0 respectively.The high Seebeck coefficient ≈ 7863 μV/K,reasonably good power factor ≈7.2×10^（-4） W/（m·K^2） and thermoelectric figure of merit ≈1.2 observed at 42 K suggests that,on further work,the prepared SnSe thin films can also be considered as a possible candidate for cryogenic thermoelectric applications.展开更多
Organic semiconductors(OSCs)possess diverse chemical structures and tailored optoelectronic properties via simple chemical modifications,so increasing use of them are found in efficient visible-light photo-catalysis.H...Organic semiconductors(OSCs)possess diverse chemical structures and tailored optoelectronic properties via simple chemical modifications,so increasing use of them are found in efficient visible-light photo-catalysis.However,the weak chemical bonds and the poor charge behavior(e.g.,low concentration of free charge carriers,low carrier mobility)intrinsic in them,always incur quite limited stability and efficiency.Therefore,the assembly of them into refined nanostructures or nanocomposites is usually proposed to enhance their optoelectronic properties,as well as the photocatalytic efficiency and reliability.Zero-dimensional(0D)nanoparticles are low in size and hence high specific surface area(SSA);One-dimensional(1D)nanostructures are usually arranged in an orderly long range thus leading to low surface defect density and increased carrier mobility;Two-dimensional(2D)nanostructures are particularly capa-ble of enhancing the photogenerated charge utilization because of their large reaction sites and shortened charge transport length.Furthermore,the building of heterogeneous interfaces in the nanocomposites can effectively facilitate the special charge separation.All these highlight the importance of organic nanos-tructures in improving the photocatalytic activity and stability.Therefore,organic semiconductor nanostructures(OSNs)have been increasingly used in the photocatalytic water splitting into H_(2) and O_(2),CO_(2) reduction,pollutant decomposition,disinfection,etc.In this review,we first examine the important optoelectronic properties of OSNs that govern the photocatalytic processes;we then analyze different classes of OSNs and their mechanistic pathways,with an emphasis on the structure-property relationships;we also introduced various photocatalytic applications of OSNs;we lastly propose the challenges and future outlook in real use.展开更多
Diarylethene derivatives are a class of fascinating photochromic materials because of their open and closed isomers with different absorption spectra and many other characteristics.To reveal the detailed structure and...Diarylethene derivatives are a class of fascinating photochromic materials because of their open and closed isomers with different absorption spectra and many other characteristics.To reveal the detailed structure and optoelectronic properties as well as the effect of metal centres and substituents on them,a systematic study on a series of diarylethene derivatives and their Re(I),Pt(II),and Ir(III) complexes was performed via theoretical calculation.The optimized geometries,electronic properties,frontier molecular orbitals,ionization potentials,electron affinities,reorganization energies,and absorption spectra for both of their open-and closed-isomers have been calculated and analyzed.Metal-coordination and substituents exhibit great influence on the photophysical,charge-injection and-transporting characteristics.In addition,the binding of F-with the boron atom of dimesitylboryl group through Lewis acid/base interactions also induces great changes of structural,photophysical and electronic properties for these diarylethene derivatives,and consequently the compound with the substituent of dimesitylboryl group can be used as selective near-infrared phosphorescent F-probe.展开更多
Modulation between optical and ferroelectric properties was realized in a lateral structured ferroelectric CuInP_(2)S_(6)(CIPS)/semiconductor MoS_(2) van der Waals heterojunction.The ferroelectric hysteresis loop area...Modulation between optical and ferroelectric properties was realized in a lateral structured ferroelectric CuInP_(2)S_(6)(CIPS)/semiconductor MoS_(2) van der Waals heterojunction.The ferroelectric hysteresis loop area was modulated by the optical field.Two types of photodetection properties can be realized in a device by changing the ON and OFF states of the ferroelectric layer.The device was used as a photodetector in the OFF state but not in the ON state.The higher tunnelling electroresistance(~1.4×10^(4))in a lateral structured ferroelectric tunnelling junction was crucial,and it was analyzed and modulated by the barrier height and width of the ferroelectric CIPS/semiconductor MoS_(2) Schottky junction.The new parameter of the ferroelectric hysteresis loop area as a function of light intensity was introduced to analyze the relationship between the ferroelectric and photodetection properties.The proposed device has potential application as an optoelectronic sensory cell in the biological nervous system or as a new type of photodetector.展开更多
A facile procedure for the synthesis ofdithieno[5,6-b：11,12-b＇]coronene-2,3,8,9-tetracarboxylic tetra（2- ethylhexyl）ester （DTCTI＇E-EH） from readily available perylene-3,4,9,10-tetracaroboxylic dianhydride is de...A facile procedure for the synthesis ofdithieno[5,6-b：11,12-b＇]coronene-2,3,8,9-tetracarboxylic tetra（2- ethylhexyl）ester （DTCTI＇E-EH） from readily available perylene-3,4,9,10-tetracaroboxylic dianhydride is described. The electronic properties of DTCTTE-EH were elucidated on the basis of UV-vis spectra, emission spectrum and electrochemical measurement, which demonstrate that DTCTTE is a new class of components for promising semiconducting materials.展开更多
Two new thioantimonates,(NH4)2Sb10S16(1)and K1.4(NH4)0.6Sb10S16(2),have been synthesized by solvothermal method with the yields of 80%and 85%,respectively.Single-crystal X-ray diffraction(SCXRD)study reveals that 1 cr...Two new thioantimonates,(NH4)2Sb10S16(1)and K1.4(NH4)0.6Sb10S16(2),have been synthesized by solvothermal method with the yields of 80%and 85%,respectively.Single-crystal X-ray diffraction(SCXRD)study reveals that 1 crystallizes in the monoclinic space group of Pn with a=8.1284(4),b=19.4587(9),c=9.1030(4)A,β=91.736(5)°,V=1439.14(12)A^(3),Z=2,Dc=4.077 g·cm^(-3),F(000)=1576,μ=10.389 mm^(-1),R=0.0343 and w R=0.0624(I>2σ(I));2 also crystallizes in the monoclinic space group of Pn with a=8.0989(6),b=19.3730(17),c=9.0411(6)A,β=91.879(6)°,V=1417.79(19)A^(3),Z=2,Dc=4.207 g·cm^(-3),F(000)=1598,μ=10.748 mm-1,R=0.0323 and w R=0.0664(I>2σ(I)).The anionic frameworks of two compounds both feature two-dimensional(2D)[Sb10S16]n2n-layers.The stabilities and optoelectronic properties of 1 and 2 have been characterized.In particular,they are stable under acidic or alkaline conditions(pH=0 or 12.5),showing excellent acid-based resistance.展开更多
The optoelectronic and magnetic properties of pure HoMnO3 and Ho0.67T0.33MnO3 （T = La, Y） alloys in hexagonal phase are theoretically investigated by using the first-principles calculations. The investigations are p...The optoelectronic and magnetic properties of pure HoMnO3 and Ho0.67T0.33MnO3 （T = La, Y） alloys in hexagonal phase are theoretically investigated by using the first-principles calculations. The investigations are performed by means of the density functional theory through using the spin polarized generalized gradient approximation plus the Hubbard potential （SPGGA ＋ U, Ueff =3 eV）. The studied material HoMnO3 exhibits two indirect band gaps： 1.58 eV for the spin- up state and 0.72 eV for the spin-down state along the S-G direction within the SPGGA ＋ U approximation. It is found that the band gap of pure HoMnO3 for the spin-up state increases with increasing La and Y dopants. The results show that all of the studied materials have semi-metallic behaviors for the spin-up state and semiconducting character for the spin-down state. The substitutions of La and Y for Ho in HoMnO3 cause the static dielectric constant （ε0） to increase in the x direction but to decrease in the z direction. The calculated optical conductivity spectrum of HoMnO3 in a low energy range is in good agreement with the recent experimental data.展开更多
Al-doped ZnO(AZO)thin films were deposited on glass substrates by rf-sputtering at room temperature.The effects of substrate rotation speed(ωS)on the morphological,structural,optical and electrical properties were in...Al-doped ZnO(AZO)thin films were deposited on glass substrates by rf-sputtering at room temperature.The effects of substrate rotation speed(ωS)on the morphological,structural,optical and electrical properties were investigated.SEM transversal images show that the substrate rotation produces dense columnar structures which were found to be better defined under substrate rotation.AFM images show that the surface particles of the samples formed under substrate rotation are smaller and denser than those of a stationary one,leading to smaller grain sizes.XRD results show that all films have hexagonal wurtzite structure and preferred c-axis orientation with a tensile stress along the c-axis.The average optical transmittance was above90%in UV-Vis region.The lowest resistivity value(8.5×10?3Ω·cm)was achieved atωS=0r/min,with a carrier concentration of1.8×1020cm?3,and a Hall mobility of4.19cm2/(V·s).For all other samples,the substrate rotation induced changes in the carrier concentration and Hall mobility which resulted in the increasing of electrical resistivity.These results indicate that the morphology,structure,optical and electrical properties of the AZO thin films are strongly affected by the substrate rotation speed.展开更多
The solar cell based on organic-inorganic hybrid halide perovskite is progressing amazingly fast in last decade owing to the robust experimental and theoretical investigations. First-principles calculation is one of t...The solar cell based on organic-inorganic hybrid halide perovskite is progressing amazingly fast in last decade owing to the robust experimental and theoretical investigations. First-principles calculation is one of the crucial ways to understand the nature of the materials and is practically helpful to the development and application of perovskite solar cells. Here, we briefly review the progress of theoretical studies we made in the last few years on the modification of electronic structures of perovskites by varying the composition, configuration, and structure, and the new understandings into the defect properties of halide perovskites for solar cell and optoelectronic applications. These understandings are foundations and new starting points for future investigations. We hope the experience and inspiration gained from these studies encourage more theoretical explorations for new functional perovskite-based materials.展开更多
In recent years, great progress has been made in research and development of small-molecule organic materials with various low-dimensional nanostructures. This paper presents a comprehensive review of recent research ...In recent years, great progress has been made in research and development of small-molecule organic materials with various low-dimensional nanostructures. This paper presents a comprehensive review of recent research progress in this field, including preparation, electronic and optoelectronic properties and applications. First, an introduction gives to the reprecipitation, soft templates methods, and progress in synthesis and morphological control of low-dimensional small-molecule organic nanomaterials. Their unique optical and electronic properties and research progress in these aspects are reviewed and discussed in detail. Applications based on low-dimensional small-molecule organic nanomaterials are briefly described. Finally, some perspectives to the future development of this field are addressed.展开更多
文摘The exploitation of fossil resources to meet humanity’s energy needs is the root cause of the climate warming phenomenon facing the planet. In this context, non-carbon-based energies, such as photovoltaic energy, are identified as crucial solutions. Organic perovskites MAPbI<sub>3</sub> and FAPbI<sub>3</sub>, characterized by their abundance, low cost, and ease of synthesis, are emerging as candidates for study to enhance their competitiveness. It is within this framework that this article presents a comparative analysis of the performances of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> perovskites in the context of photovoltaic devices. The analysis focuses on the optoelectronic characteristics and stability of these high-potential materials. The optical properties of perovskites are rigorously evaluated, including band gaps, photoluminescence, and light absorption, using UV-Vis spectroscopy and photoluminescence techniques. The crystal structure is characterized by X-ray diffraction, while film morphology is examined through scanning electron microscopy. The results reveal significant variations between the two types of perovskites, directly impacting the performance of resulting solar devices. Simultaneously, the stability of perovskites is subjected to a thorough study, exposing the materials to various environmental conditions, highlighting key determinants of their durability. Films of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> demonstrate distinct differences in terms of topography, optical performance, and stability. Research has unveiled that planar perovskite solar cells based on FAPbI<sub>3</sub> offer higher photoelectric conversion efficiency, surpassing their MAPbI<sub>3</sub>-based counterparts in terms of performance. These advancements aim to overcome stability constraints and enhance the long-term durability of perovskites, ultimately aiming for practical application of these materials. This comprehensive comparative analysis provides an enlightened understanding of the optoelectronic performance and stability of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> perovskites, which is critically important to guide future research and development of solar devices that are both more efficient and sustainable.
基金supported by open research fund from Guangxi Key Laboratory of New Energy and Building Energy Saving, China
文摘Al-doped ZnO thin films were prepared on glass substrate using an ultra-high density target by RF magnetron sputtering at room temperature. The microstructure, surface morphology, optical and electrical properties of AZO thin films were investigated by X-ray diffractometer, scanning electron microscope, UV-visible spectrophotometer, four-point probe method, and Hall-effect measurement system. The results showed that all the films obtained were polycrystalline with a hexagonal structure and average optical transmittance of AZO thin films was over 85 % at different sputtering powers. The sputtering power had a great effect on optoelectronic properties of the AZO thin films, especially on the resistivity. The lowest resistivity of 4.5×10^-4 Ω·cm combined with the transmittance of 87.1% was obtained at sputtering power of 200 W. The optical band gap varied between 3.48 and 3.68 eV.
基金supported by the National Natural Science Foundation of China(21063009)the Natural Science Foundation of Inner Mongolia(2012MS0218)+1 种基金the Talent Development Foundation of Inner Monguliathe Graduate Student Innovation Foundation of Inner Mongulia Normal University(CXJJS11046)
文摘The perfluoroalkyl substances（PFS） have attracted considerable attention in recent years as a persistent global pollutant to be able to bioaccumulate in higher organisms.In this paper,theoretical analysis on electronic structures,optoelectronic properties and absorption spectra properties of the perflurooctane sulfonate（PFOS） in gas phase have been investigated by using the DFT/TD-DFT method.The geometric structures,electrostatic potentials,energy gaps,ionization potentials,electron affinities,frontier molecular orbital,excitation energies and absorption spectra for the ground state of PFOS were calculated.The result indicates that the ability of accepting electron of neutral PFOS is larger than that of anionic PFOS,while the electron excited by UV irradiation from HOMO to LUMO in the anionic PFOS is easier than that in the neutral PFOS.
文摘Advanced GGA ＋ U（Hubbard） and modified Becke–Johnson（mBJ） techniques are used for the calculation of the structural, electronic, and optical parameters of α-Al2-x CoxO3（x = 0.0, 0.167） compounds. The direct band gaps calculated by GGA and m BJ for pure alumina are 6.3 eV and 8.5 eV, respectively. The m BJ approximation provides results very close to the experimental one（8.7 eV）. The substitution of Al with Co reduces the band gap of alumina. The wide and direct band gap of the doped alumina predicts that it can efficiently be used in optoelectronic devices. The optical properties of the compounds like dielectric functions and energy loss function are also calculated. The rhombohedral structure of theα-Al2-x CoxO3（x = 0.0, 0.167） compounds reveal the birefringence properties.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61505197 and 61334009the National High-Technology Research and Development Program of China under Grant No 2014AA032604
文摘The effect of back-diffusion of Mg dopants on optoelectronic characteristics of InGaN-based green light-emitting diodes （LEDs） is investigated. The LEDs with less Mg back-diffusion show blue shifts of longer wavelengths and larger wavelengths with the increasing current, which results from the Mg-dopant-related polarization screening. The LEDs show enhanced efficiency with the decreasing Mg back-diffusion in the lower current region. Light outputs follow the power law L α I^m, with smaller parameter m in the LEDs with less Mg back-diffusion, indicating a lower density of trap states. The trap-assisted tunneling current is also suppressed by reducing Mg- defect-related nonradiative centers in the active region. Furthermore, the forward current-voltage characteristics are improved.
基金Supported by UGC,New Delhi through UGC-BSR(JRF)fellowships
文摘Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.
基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0305700 and 2016YFA0401804)the National Natural Science Foundation of China(Grant Nos.11574323,11704387,U1632275,11304321,11604340,and 61774136)+1 种基金the Natural Science Foundation of Anhui Province,China(Grant No.1708085QA19)the Director’s Fund of Hefei Institutes of Physical Science,Chinese Academy of Sciences(Grant No.YZJJ201621)
文摘PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and indirect-to-direct gap transition under strain; however, these properties have not been verified experimentally. Here we report the first experimental exploration of its optoelectronic properties under external pressure. We find that the photocurrent is weakly pressuredependent below 3 GPa but increases significantly in the pressure range of 3 GPa–4 GPa, with a maximum ～ 6 times higher than that at ambient pressure. X-ray diffraction data shows that no structural phase transition can be observed up to26.8 GPa, which indicates a stable lattice structure of PtS2 under high pressure. This is further supported by our Raman measurements with an observation of linear blue-shifts of the two Raman-active modes to 6.4 GPa. The pressure-enhanced photocurrent is related to the indirect-to-direct/quasi-direct bandgap transition under pressure, resembling the gap behavior under compression strain as predicted theoretically.
基金Project supported by the National Natural Science Foundation of China (Grant No 50575113)Program for NCET
文摘This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal--semiconductor metal （MSM） structure by dieleetrophoresis and studying on its electrical characteristics by using current-voltage （Ⅰ - Ⅴ） measurements. An electronic model with two back to back Sehottky diodes in series with a semiconductor of nanowires was established to study the electrical transport of the MSM structures. By fitting the measured Ⅰ - Ⅴ characteristics using the proposed model, the parameters of the Schottky contacts and the resistance of nanowires could be acquired. The photoelectric properties of the MSM structures were also investigated by analysing the measurements of the electrical transports under various light intensities. The deduced results demonstrate that ZnO nanowires and their Schottky contacts with Au electrodes both contribute to photosensitivity and the MSM structures with ZnO nanowires are potentially applicable for photonic devices.
基金the National Natural Science Foundation of China (Nos.22375059, 22005133, 51922039 and52273174)Shenzhen Science and Technology Program (No.RCJC20200714114434015)+1 种基金Science and Technology Innovation Program of Hunan Province (No.2020RC5033)National Key Research and Development Program of China (No.2020YFC1807302) for financial support。
文摘While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B_(2)S_(2) and Syn-B_(2)S_(2), as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10^(-3)cm^(2)V^(-1)s^(-1)were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.
文摘The influence of substrate temperature and nozzle-to-substrate distance（NSD） on the structural,morphological, optical and electrical properties of Sb：SnO_2 thin films prepared by chemical spray pyrolysis has been analyzed.The structural,morphological,optical and electrical properties were characterized by using XRD,SEM, UV-visible spectrophotometry and Hall effect measurement techniques.It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the（200） reflection.The pyramidal crystallites formed due to coalescence were observed from SEM images.The values of highest conductivity,optical transmittance and figure of merit of about 1449（Ω·cm）^（-1）,70%and 5.2×10^（-3）□/Ω,respectively,were observed for a typical film deposited using optimal conditions（substrate temperature = 500℃and NSD = 30 cm）.
基金University Grants Commission (UGC), Government of India for financial assistance in the form of Research Fellowship in Science for Meritorious Students (RFSMS)
文摘SnSe thin films of thickness 180 nm have been deposited on glass substrates by reactive evaporation at an optimized substrate temperature of 523 ± 5 K and pressure of 10^（-5） mbar.The as-prepared SnSe thin films are characterized for their structural,optical and electrical properties by various experimental techniques.The p-type conductivity,near-optimum direct band gap,high absorption coefficient and good photosensitivity of the SnSe thin film indicate its suitability for photovoltaic applications.The optical constants,loss factor,quality factor and optical conductivity of the films are evaluated.The results of Hall and thermoelectric power measurements are correlated to determine the density of states,Fermi energy and effective mass of carriers and are obtained as 2.8×10^（17）cm^（-3）,0.03 eV and 0.05m_0 respectively.The high Seebeck coefficient ≈ 7863 μV/K,reasonably good power factor ≈7.2×10^（-4） W/（m·K^2） and thermoelectric figure of merit ≈1.2 observed at 42 K suggests that,on further work,the prepared SnSe thin films can also be considered as a possible candidate for cryogenic thermoelectric applications.
基金Scientific and Technological Innovation Foundation of Shunde Graduate School,USTB (BK19AE027BK20BE022)
文摘Organic semiconductors(OSCs)possess diverse chemical structures and tailored optoelectronic properties via simple chemical modifications,so increasing use of them are found in efficient visible-light photo-catalysis.However,the weak chemical bonds and the poor charge behavior(e.g.,low concentration of free charge carriers,low carrier mobility)intrinsic in them,always incur quite limited stability and efficiency.Therefore,the assembly of them into refined nanostructures or nanocomposites is usually proposed to enhance their optoelectronic properties,as well as the photocatalytic efficiency and reliability.Zero-dimensional(0D)nanoparticles are low in size and hence high specific surface area(SSA);One-dimensional(1D)nanostructures are usually arranged in an orderly long range thus leading to low surface defect density and increased carrier mobility;Two-dimensional(2D)nanostructures are particularly capa-ble of enhancing the photogenerated charge utilization because of their large reaction sites and shortened charge transport length.Furthermore,the building of heterogeneous interfaces in the nanocomposites can effectively facilitate the special charge separation.All these highlight the importance of organic nanos-tructures in improving the photocatalytic activity and stability.Therefore,organic semiconductor nanostructures(OSNs)have been increasingly used in the photocatalytic water splitting into H_(2) and O_(2),CO_(2) reduction,pollutant decomposition,disinfection,etc.In this review,we first examine the important optoelectronic properties of OSNs that govern the photocatalytic processes;we then analyze different classes of OSNs and their mechanistic pathways,with an emphasis on the structure-property relationships;we also introduced various photocatalytic applications of OSNs;we lastly propose the challenges and future outlook in real use.
基金supported by the National Basic Research Program of China (973 Program,2009CB930601 and 2012CB933301)National Natural Science Foundation of China (21174064,21171098)+4 种基金Natural Science Fund for Colleges and Universities in Jiangsu Province(10KJB430010)the Ministry of Education of China (IRT1148)Key Projects in Jiangsu Province for International Cooperation (BZ2010043)Nanjing University of Posts and Telecommunications (NY210029)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Diarylethene derivatives are a class of fascinating photochromic materials because of their open and closed isomers with different absorption spectra and many other characteristics.To reveal the detailed structure and optoelectronic properties as well as the effect of metal centres and substituents on them,a systematic study on a series of diarylethene derivatives and their Re(I),Pt(II),and Ir(III) complexes was performed via theoretical calculation.The optimized geometries,electronic properties,frontier molecular orbitals,ionization potentials,electron affinities,reorganization energies,and absorption spectra for both of their open-and closed-isomers have been calculated and analyzed.Metal-coordination and substituents exhibit great influence on the photophysical,charge-injection and-transporting characteristics.In addition,the binding of F-with the boron atom of dimesitylboryl group through Lewis acid/base interactions also induces great changes of structural,photophysical and electronic properties for these diarylethene derivatives,and consequently the compound with the substituent of dimesitylboryl group can be used as selective near-infrared phosphorescent F-probe.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11874244 and 11974222)。
文摘Modulation between optical and ferroelectric properties was realized in a lateral structured ferroelectric CuInP_(2)S_(6)(CIPS)/semiconductor MoS_(2) van der Waals heterojunction.The ferroelectric hysteresis loop area was modulated by the optical field.Two types of photodetection properties can be realized in a device by changing the ON and OFF states of the ferroelectric layer.The device was used as a photodetector in the OFF state but not in the ON state.The higher tunnelling electroresistance(~1.4×10^(4))in a lateral structured ferroelectric tunnelling junction was crucial,and it was analyzed and modulated by the barrier height and width of the ferroelectric CIPS/semiconductor MoS_(2) Schottky junction.The new parameter of the ferroelectric hysteresis loop area as a function of light intensity was introduced to analyze the relationship between the ferroelectric and photodetection properties.The proposed device has potential application as an optoelectronic sensory cell in the biological nervous system or as a new type of photodetector.
基金supported by NSFC(Nos.51073124 and 21031006)Research Fund for the Doctoral Program of Higher Education of China(No.20100143120002)Natural Science Foundation of Hubei Province(No.2011CDA102)
文摘A facile procedure for the synthesis ofdithieno[5,6-b：11,12-b＇]coronene-2,3,8,9-tetracarboxylic tetra（2- ethylhexyl）ester （DTCTI＇E-EH） from readily available perylene-3,4,9,10-tetracaroboxylic dianhydride is described. The electronic properties of DTCTTE-EH were elucidated on the basis of UV-vis spectra, emission spectrum and electrochemical measurement, which demonstrate that DTCTTE is a new class of components for promising semiconducting materials.
基金supported by the National Science Foundations of China(Nos.22076185 and 21771183)the Natural Science Foundation of Fujian Province(No.2020J06033)FJIRSM&IUE Joint Research Fund(No.RHZX-2018-005)。
文摘Two new thioantimonates,(NH4)2Sb10S16(1)and K1.4(NH4)0.6Sb10S16(2),have been synthesized by solvothermal method with the yields of 80%and 85%,respectively.Single-crystal X-ray diffraction(SCXRD)study reveals that 1 crystallizes in the monoclinic space group of Pn with a=8.1284(4),b=19.4587(9),c=9.1030(4)A,β=91.736(5)°,V=1439.14(12)A^(3),Z=2,Dc=4.077 g·cm^(-3),F(000)=1576,μ=10.389 mm^(-1),R=0.0343 and w R=0.0624(I>2σ(I));2 also crystallizes in the monoclinic space group of Pn with a=8.0989(6),b=19.3730(17),c=9.0411(6)A,β=91.879(6)°,V=1417.79(19)A^(3),Z=2,Dc=4.207 g·cm^(-3),F(000)=1598,μ=10.748 mm-1,R=0.0323 and w R=0.0664(I>2σ(I)).The anionic frameworks of two compounds both feature two-dimensional(2D)[Sb10S16]n2n-layers.The stabilities and optoelectronic properties of 1 and 2 have been characterized.In particular,they are stable under acidic or alkaline conditions(pH=0 or 12.5),showing excellent acid-based resistance.
文摘The optoelectronic and magnetic properties of pure HoMnO3 and Ho0.67T0.33MnO3 （T = La, Y） alloys in hexagonal phase are theoretically investigated by using the first-principles calculations. The investigations are performed by means of the density functional theory through using the spin polarized generalized gradient approximation plus the Hubbard potential （SPGGA ＋ U, Ueff =3 eV）. The studied material HoMnO3 exhibits two indirect band gaps： 1.58 eV for the spin- up state and 0.72 eV for the spin-down state along the S-G direction within the SPGGA ＋ U approximation. It is found that the band gap of pure HoMnO3 for the spin-up state increases with increasing La and Y dopants. The results show that all of the studied materials have semi-metallic behaviors for the spin-up state and semiconducting character for the spin-down state. The substitutions of La and Y for Ho in HoMnO3 cause the static dielectric constant （ε0） to increase in the x direction but to decrease in the z direction. The calculated optical conductivity spectrum of HoMnO3 in a low energy range is in good agreement with the recent experimental data.
文摘Al-doped ZnO(AZO)thin films were deposited on glass substrates by rf-sputtering at room temperature.The effects of substrate rotation speed(ωS)on the morphological,structural,optical and electrical properties were investigated.SEM transversal images show that the substrate rotation produces dense columnar structures which were found to be better defined under substrate rotation.AFM images show that the surface particles of the samples formed under substrate rotation are smaller and denser than those of a stationary one,leading to smaller grain sizes.XRD results show that all films have hexagonal wurtzite structure and preferred c-axis orientation with a tensile stress along the c-axis.The average optical transmittance was above90%in UV-Vis region.The lowest resistivity value(8.5×10?3Ω·cm)was achieved atωS=0r/min,with a carrier concentration of1.8×1020cm?3,and a Hall mobility of4.19cm2/(V·s).For all other samples,the substrate rotation induced changes in the carrier concentration and Hall mobility which resulted in the increasing of electrical resistivity.These results indicate that the morphology,structure,optical and electrical properties of the AZO thin films are strongly affected by the substrate rotation speed.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2016YFB0700700)the National Natural Science Foundation of China (Grant Nos. 51672023, 11634003, and U1930402)the Creative Talents Plan in CPSF, China (Grant No. BX2018033).
文摘The solar cell based on organic-inorganic hybrid halide perovskite is progressing amazingly fast in last decade owing to the robust experimental and theoretical investigations. First-principles calculation is one of the crucial ways to understand the nature of the materials and is practically helpful to the development and application of perovskite solar cells. Here, we briefly review the progress of theoretical studies we made in the last few years on the modification of electronic structures of perovskites by varying the composition, configuration, and structure, and the new understandings into the defect properties of halide perovskites for solar cell and optoelectronic applications. These understandings are foundations and new starting points for future investigations. We hope the experience and inspiration gained from these studies encourage more theoretical explorations for new functional perovskite-based materials.
基金supported by the National Natural Science Foundation of China (NSFC) under Grant No.60736005 and 60425101-1the Foundation for Innovative Research Groups of the NSFC under Grant No.60721001+3 种基金Provincial Project under grant No.9140A02060609DZ0208 and No.20090185110020Program for New Century Excellent Talents in University under Grant No.NCET-06-0812 and No. 08-0088SRF for ROCS,SEM under Grant No.GGRYJJ08-05Young Excellent Project of Sichuan Province under Grant No.09ZQ026-074
文摘In recent years, great progress has been made in research and development of small-molecule organic materials with various low-dimensional nanostructures. This paper presents a comprehensive review of recent research progress in this field, including preparation, electronic and optoelectronic properties and applications. First, an introduction gives to the reprecipitation, soft templates methods, and progress in synthesis and morphological control of low-dimensional small-molecule organic nanomaterials. Their unique optical and electronic properties and research progress in these aspects are reviewed and discussed in detail. Applications based on low-dimensional small-molecule organic nanomaterials are briefly described. Finally, some perspectives to the future development of this field are addressed.
