Room temperature low threshold lasing of green GaNbased vertical cavity surface emitting laser(VCSEL)was demonstrated under continuous wave(CW)operation.By using self-formed InGaN quantum dots(QDs)as the active region...Room temperature low threshold lasing of green GaNbased vertical cavity surface emitting laser(VCSEL)was demonstrated under continuous wave(CW)operation.By using self-formed InGaN quantum dots(QDs)as the active region,the VCSEL emitting at 524.0 nm has a threshold current density of 51.97 A cm^(-2),the lowest ever reported.The QD epitaxial wafer featured with a high IQE of 69.94%and theδ-function-like density of states plays an important role in achieving low threshold current.Besides,a short cavity of the device(~4.0λ)is vital to enhance the spontaneous emission coupling factor to 0.094,increase the gain coefficient factor,and decrease the optical loss.To improve heat dissipation,AlN layer was used as the current confinement layer and electroplated copper plate was used to replace metal bonding.The results provide important guidance to achieving high performance GaN-based VCSELs.展开更多
Quantum dots(QDs)have attracted wide attention from academia and industry because of their advantages such as high emitting efficiency,narrow half-peak width,and continuously adjustable emitting wavelength.QDs light e...Quantum dots(QDs)have attracted wide attention from academia and industry because of their advantages such as high emitting efficiency,narrow half-peak width,and continuously adjustable emitting wavelength.QDs light emitting diodes(QLEDs)are expected to become the next generation commercial display technology.This paper reviews the progress of QLED from physical mechanism,materials,to device engineering.The strategies to improve QLED performance from the perspectives of quantum dot materials and device structures are summarized.展开更多
Metal-halide perovskites(MHPs)have emerged as a new class of semiconductors used in perovskite solar cells(PSCs)[1-5],perovskite light-emitting diodes(PeLEDs)[6-12],photo/X-ray detectors[13-16],and memristors[17,18].P...Metal-halide perovskites(MHPs)have emerged as a new class of semiconductors used in perovskite solar cells(PSCs)[1-5],perovskite light-emitting diodes(PeLEDs)[6-12],photo/X-ray detectors[13-16],and memristors[17,18].Pe LEDs can emit different light with high purity[19,20].展开更多
We demonstrated gold nanoclusters as color tunable emissive light converters for the application of white light emitting diodes (WLEDs). A blue LED providing 460 nm to excite gold nanoclusters mixed with UV curable ma...We demonstrated gold nanoclusters as color tunable emissive light converters for the application of white light emitting diodes (WLEDs). A blue LED providing 460 nm to excite gold nanoclusters mixed with UV curable material generates broad bandwidth emission at the visible range. Increasing the amount of gold nanoclusters, the correlated color temperature of WLEDs tuned from cold white to warm white, and also results in the variation of color rendering index (CRI). The highest CRI in the experiment is 92.展开更多
Boron−nitrogen doped multiple resonance(BN-MR)emitters,characterized by B−N covalent bonds,offer distinctive advantages as pivotal building blocks for facile access to novel MR emitters featuring narrowband spectra an...Boron−nitrogen doped multiple resonance(BN-MR)emitters,characterized by B−N covalent bonds,offer distinctive advantages as pivotal building blocks for facile access to novel MR emitters featuring narrowband spectra and high efficiency.However,there remains a scarcity of exploration concerning synthetic methods and structural derivations to expand the library of novel BN-MR emitters.Herein,we present the synthesis of a BN-MR emitter,tCz[B−N]N,through a one-pot borylation reaction directed by the amine group,achieving an impressive yield of 94%.The emitter is decorated by incorporating two 3,6-di-tbutylcarbazole(tCz)units into a B−N covalent bond doped BN-MR parent molecule via para-C−π−D and para-N−π−D conjugations.This peripheral decoration strategy enhances the reverse intersystem crossing process and shifts the emission band towards the pure green region,peaking at 526 nm with a narrowband full-width at half maximum(FWHM)of 41 nm.Consequently,organic light emitting diodes(OLEDs)employing this emitter achieved a maximum external quantum efficiency(EQEmax)value of 27.7%,with minimal efficiency roll-off.Even at a practical luminance of 1000 cd·m^(−2),the device maintains a high EQE value of 24.6%.展开更多
Lateral oxidation in vertical cavity surface emitting lasers （VCSELs） is described,and its characteristics are investigated.A linear growth law is found for stripe mesas. However, oxide growth （above 435℃ ） follo...Lateral oxidation in vertical cavity surface emitting lasers （VCSELs） is described,and its characteristics are investigated.A linear growth law is found for stripe mesas. However, oxide growth （above 435℃ ） follows a nonlinear law for the two geometry mesa structures which we employ in VCSEL. Theoretical analysis indicates that mesa structure geometry influences oxide growth rate at higher temperatures.展开更多
High slope efficiency and high power selected oxide-confined 850nm VCSELs grown by MOCVD are reported.The slope efficiency and the threshold current respectively are 0 82mW/mA and 2 59mA with a 9μm diameter oxidati...High slope efficiency and high power selected oxide-confined 850nm VCSELs grown by MOCVD are reported.The slope efficiency and the threshold current respectively are 0 82mW/mA and 2 59mA with a 9μm diameter oxidation aperture at 25℃.The maximum power of 16mW is obtained at 23mA current bias.The minimum threshold current can be as low as 570μA with a 5μm diameter oxidation aperture at 25℃.The maximum saturated power is 5 5mW.展开更多
A 1.3μm low-threshold edge-emitting AlGaInAs multiple-quantum-well(MQW) laser with AlInAs-oxide confinement layers is fabricated.The Al-contained waveguide layers upper and low the active layers are oxidized as curre...A 1.3μm low-threshold edge-emitting AlGaInAs multiple-quantum-well(MQW) laser with AlInAs-oxide confinement layers is fabricated.The Al-contained waveguide layers upper and low the active layers are oxidized as current-confined layers using wet-oxidation technique.This structure provides excellent current and optical confinement,resulting in 12.9mA of a low continuous wave threshold current and 0.47W/A of a high slope efficiency of per facet at room temperature for a 5-μm-wide current aperture.Compared with the ridge waveguide laser with the same-width ridge,the threshold current of the AlInAs-oxide confinement laser has decreased by 31.7% and the slope efficiency has increased a little.Both low threshold and high slope efficiency indicate that lateral current confinement can be realized by oxidizing AlInAs waveguide layers.The full width of half maximum angles of the Al-InAs-oxide confinement laser are 21.6° for the horizontal and 36.1° for the vertical,which demonstrate the ability of the AlInAs oxide in preventing the optical field from spreading laterally.展开更多
A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,0...A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,000 cd/m2. A peak color rendering index of 90 and a relatively stable color during a wide range of luminance were obtained. In addition, it was demonstrated that the 4,40,400-tri(9-carbazoyl) triphenylamine host influenced strongly the performance of this WOLED.These results may be beneficial to the design of both material and device architecture for high-performance WOLED.展开更多
The reasons for low output power of AlGalnP Light Emitting Diodes （LEDs） have been analysed. LEDs with AlGaInP material have high internal but low external quantum efficiency and much heat generated inside especiall...The reasons for low output power of AlGalnP Light Emitting Diodes （LEDs） have been analysed. LEDs with AlGaInP material have high internal but low external quantum efficiency and much heat generated inside especially at a large injected current which would reduce both the internal and external quantum efficiencies. Two kinds of LEDs with the same active region but different window layers have been fabricated. The new window layer composed of textured 0.5 μm GaP and thin Indium-Tin-Oxide film has shown that low external quantum efficiency （EQE） has serious impaction on the internal quantum efficiency （IQE）, because the carrier distribution will change with the body temperature increasing due to the heat inside, and the test results have shown the evidence of LEDs with lower output power and bigger wavelength red shift.展开更多
Polycrystalline Gd2(MoO4)3:Dy3+ phosphors have been synthesized by high temperature solid-state reaction method. The phosphors were characterized with X-ray diffractometer, thermogravimetric analysis and different sca...Polycrystalline Gd2(MoO4)3:Dy3+ phosphors have been synthesized by high temperature solid-state reaction method. The phosphors were characterized with X-ray diffractometer, thermogravimetric analysis and different scanning calorimeter, scanning electron microscopy, and photoluminescence spectrofluorimeter. Several peaks at 351, 389, 425, 452, and 472 nm appeared in photoluminescence excitation spectrum, which matched well with the emission of the ultraviolet (UV) and blue-light emitting diode (LED) chips. Upon excitation at 389 nm UV light, intense emissions centered at 484, 575 and 668 nm were attributed to the transitions of 4F9/2→6H15/2, 4F9/2→6H13/2 and 4F9/2→6H11/2 of Dy3+, respectively. The chromaticity coordinates and correlative color temperatures have been calculated and presented in the Commission International de I’Eclairage (CIE) diagrams. The results indicated that Gd1.9(MoO4)3:Dy0.13+ with CIE coordinates of (x=0.38, y=0.41) and the correlative color temperature of 4134 K is a potential candidate for white LEDs.展开更多
InGaN quantum dot is a promising optoelectronic material, which combines the advantages of low-dimensional and wide-gap semiconductors. The growth of InGaN quantum dots is still not mature, especially the growth by me...InGaN quantum dot is a promising optoelectronic material, which combines the advantages of low-dimensional and wide-gap semiconductors. The growth of InGaN quantum dots is still not mature, especially the growth by metal--organic- vapor phase epitaxy （MOVPE）, which is challenge due to the lack of, itin-situ monitoring tool. In this paper, we reviewed the development of InGaN quantum dot growth by MOVPE, including our work on growth of near-UV, green, and red InGaN quantum dots. In addition, we also introduced the applications of InGaN quantum dots on visible light emitting diodes.展开更多
This paper reviews the recent progress in the synthesis of near-infrared(NIR) lead chalcogenide(PbX;PbX = PbS,PbSe, PbTe) quantum dots(QDs) and their applications in NIR QDs based light emitting diodes(NIR-QLEDs). It ...This paper reviews the recent progress in the synthesis of near-infrared(NIR) lead chalcogenide(PbX;PbX = PbS,PbSe, PbTe) quantum dots(QDs) and their applications in NIR QDs based light emitting diodes(NIR-QLEDs). It summarizes the strategies of how to synthesize high efficiency PbX QDs and how to realize high performance Pb X based NIR-QLEDs.展开更多
A red-emitting phosphor GdNbO4：Eu3＋,Bi3＋ was prepared by a high temperature solid-state reaction technique. The phosphor was characterized by X-ray diffraction （XRD）, particle size analyzer and fluorescence spect...A red-emitting phosphor GdNbO4：Eu3＋,Bi3＋ was prepared by a high temperature solid-state reaction technique. The phosphor was characterized by X-ray diffraction （XRD）, particle size analyzer and fluorescence spectrometer. The single phase of GdNbO4：Eu3＋,Bi3＋ was obtained at 1150~C and the average particle diameter was about 2.30 μm. Excitation and emission spectra reveal that the phosphor can be ef- ficiently excited by ultraviolet （UV） light （394 nm） and emit the strong red light of 612 nm due to the Eu3＋ transition of SD0~TF2. The opti- mum content of Eu3＋ doped in the phosphor GdNbOn：Eu3＋ is 20mo1%. The phosphor Gdo.80NbO4：0.20Eu3＋,0.03Bi3＋ shows much stronger photoluminescence intensity and better chromaticity coordinates （x=0.642, 0.352） than GdNbO4：Eu3＋. It is confirmed that Gdo.80NbO4：0.20Eu3＋,0.03Bi3＋ is a potential candidate for near-UV chip-based white light emitting diodes.展开更多
White light-emitting diodes(WLEDs),as key infrastructure,play an important role in the field of lighting and display.In the past few decades,many methods were developed to prepare WLEDs.A common strategy is to use blu...White light-emitting diodes(WLEDs),as key infrastructure,play an important role in the field of lighting and display.In the past few decades,many methods were developed to prepare WLEDs.A common strategy is to use blue LEDs to excite yttrium aluminum garnet(YAG)phosphors and generate composite white light,which is now the main technology for commercial lighting.In 2014,Nobel Prize in Physics was awarded to Nakamura et al.for their contribution to blue LEDs[1,2].展开更多
lNovel lithium doped tris 8 hydroxylquinoline aluminium(Alq3:Li) layer is deposited between emission layer and electron injection aluminium electrode as an electron injection assistant layer in different organic lig...lNovel lithium doped tris 8 hydroxylquinoline aluminium(Alq3:Li) layer is deposited between emission layer and electron injection aluminium electrode as an electron injection assistant layer in different organic light emitting diodes(OLED) to lower the electron injection barrier. In these devices, Alq3 is used as emission layer, and a bilayer film of N,N bis (1 naphhyl) N,N diphenyl 1,1 biphenyle 4,4' diamine(NPB) and 4,4,4' tris(3 methyl phenylphenylamino) triphenylamine( m MTDATA) used as hole transport layer(HTL). The electroluminescent performance of devices with different thicknesses of Alq3∶Li shows that the insertion of the lithium doped Alq3 layer can reduce the turn on voltage by at least 2 volts, and the stability of devices with this lithium doped Alq3 layer is improved too. It can also change the efficiency of devices. Compared with an ultra thin lithium fluoride(LiF) layer, Alq3∶Li sheet gives similar effects but higher efficiency and can be much thicker and hence it is easier to control the deposition.展开更多
Organic light emitting diodes employing magnesium doped electron acceptor 3, 4, 9, 10 perylenetetracarboxylic dianhydride （Mg：PTCDA） as electron injection layer and silver as cathode were demonstrated. As compared ...Organic light emitting diodes employing magnesium doped electron acceptor 3, 4, 9, 10 perylenetetracarboxylic dianhydride （Mg：PTCDA） as electron injection layer and silver as cathode were demonstrated. As compared to Mg ： Ag cathode, the combination of the Mg ： PTCDA layer and silver provided enhanced electron injection into tris （8- quinolinolato） aluminium. The device with 1 ： 2 Mg ： PTCDA and Ag showed an increase of about 12% in the maximum current efficiency, mainly due to the improved hole-electron balance, and an increase of about 28% in the maximum power efficiency, as compared to the control device using Mg ： Ag cathode. The properties of Mg ： PTCDA composites were studied as well.展开更多
A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μm complementary metal-oxide-semiconductor technology. This device is capable of versatile working modes： it can emit ...A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μm complementary metal-oxide-semiconductor technology. This device is capable of versatile working modes： it can emit visible to near infra-red （NIR） light （the spectrum ranges from 500 nm to 1000 nm） in reverse bias avalanche breakdown mode with working voltage between 8.35 V-12 V and emit NIR light （the spectrum ranges from 900 nm to 1300 nm） in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.展开更多
This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes （flip chip LEDs） on Si substrates. The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based...This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes （flip chip LEDs） on Si substrates. The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based LED were investigated. In the sequent aging tests, samples were driven with a constant current of 80 mA for hundreds hours at the room temperature. It was found that the electroluminescence （EL） intensity variation had a large correlation to the ultrasonic power, and then to the bonding temperature and force. A high bonding temperature and ultrasonic power and a proper bonding force improved the EL intensity significantly. It was contributed to a strong atom inter-diffusion forming a stable joint at the bonding interface, The temperature fluctuation in the aging test was the main factor to generate a high inner stress forming delamination at the interface between the chip and Au bump. As a result, delamination had retarded the photons to emit out of the LED packaging and decay its EL intensity.展开更多
We characterized the 6,12-bis{[N-（3,4-dimethylphenyl）-N-（2,4,5-trimethylphenyl）]amino} chrysene （BmPAC）, which has been proven to be a blue fluorescent emission with high EL efficiency. The blue fluorescent devi...We characterized the 6,12-bis{[N-（3,4-dimethylphenyl）-N-（2,4,5-trimethylphenyl）]amino} chrysene （BmPAC）, which has been proven to be a blue fluorescent emission with high EL efficiency. The blue fluorescent device exhibits good performance with an external quantum efficiency of 5.8% and current efficiency of 8.9 cd/A, respectively. Using BmPAC, we also demonstrate a hybrid phosphorescence/fluorescence white organic light-emitting device （WOLED） with high efficiency of 36.3 cd/A. In order to improve the relative intensity of blue light, we plus a blue light-emitting layer （BEML） in front of the orange light emitting layer （YEML） to take advantage of the excess singlet excitons. With the new emitting layer of BEML/YEML/BEML, we demonstrate the fluorescence/phosphorescence/fluorescence WOLED exhibits good performance with a current efficiency of 47 cd/A and an enhanced relative intensity of blue light.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.U21A20493,62104204,and 62234011)the National Key Research and Development Program of China(No.2017YFE0131500)the President’s Foundation of Xiamen University(No.20720220108).
文摘Room temperature low threshold lasing of green GaNbased vertical cavity surface emitting laser(VCSEL)was demonstrated under continuous wave(CW)operation.By using self-formed InGaN quantum dots(QDs)as the active region,the VCSEL emitting at 524.0 nm has a threshold current density of 51.97 A cm^(-2),the lowest ever reported.The QD epitaxial wafer featured with a high IQE of 69.94%and theδ-function-like density of states plays an important role in achieving low threshold current.Besides,a short cavity of the device(~4.0λ)is vital to enhance the spontaneous emission coupling factor to 0.094,increase the gain coefficient factor,and decrease the optical loss.To improve heat dissipation,AlN layer was used as the current confinement layer and electroplated copper plate was used to replace metal bonding.The results provide important guidance to achieving high performance GaN-based VCSELs.
基金Project supported by Leading innovation and entrepreneurship team of Zhejiang Province of China (Grant No.2021R01003)Science and Technology Innovation 2025 Major Project of Ningbo (Grant No.2022Z085)+2 种基金Ningbo 3315 Programme (Grant No.2020A-01-B)YONGJIANG Talent Introduction Programme (Grant No.2021A-038-B)Zhujiang Talent Programme (Grant No.2016LJ06C621)。
文摘Quantum dots(QDs)have attracted wide attention from academia and industry because of their advantages such as high emitting efficiency,narrow half-peak width,and continuously adjustable emitting wavelength.QDs light emitting diodes(QLEDs)are expected to become the next generation commercial display technology.This paper reviews the progress of QLED from physical mechanism,materials,to device engineering.The strategies to improve QLED performance from the perspectives of quantum dot materials and device structures are summarized.
基金the National Natural Science Foundation of China (62234004,62175226)the National Natural Science Foundation of China (21961160720)+4 种基金the National Key Research and Development Program of China (2022YFA1204800)the University Synergy Innovation Program of Anhui Province (GXXT2022-009)the China Postdoctoral Science Foundation (2022M723006)the National Key Research and Development Program of China (2022YFB3803300)the open research fund of Songshan Lake Materials Laboratory (2021SLABFK02)。
文摘Metal-halide perovskites(MHPs)have emerged as a new class of semiconductors used in perovskite solar cells(PSCs)[1-5],perovskite light-emitting diodes(PeLEDs)[6-12],photo/X-ray detectors[13-16],and memristors[17,18].Pe LEDs can emit different light with high purity[19,20].
文摘We demonstrated gold nanoclusters as color tunable emissive light converters for the application of white light emitting diodes (WLEDs). A blue LED providing 460 nm to excite gold nanoclusters mixed with UV curable material generates broad bandwidth emission at the visible range. Increasing the amount of gold nanoclusters, the correlated color temperature of WLEDs tuned from cold white to warm white, and also results in the variation of color rendering index (CRI). The highest CRI in the experiment is 92.
基金financial support from the National Natural Science Foundation of China(Nos.52303253 and 52273198)Yunnan Fundamental Research Project(No.202301BF070001-008)the Yunling Scholar Project of"Yunnan Revitalization Talent Support Program".
文摘Boron−nitrogen doped multiple resonance(BN-MR)emitters,characterized by B−N covalent bonds,offer distinctive advantages as pivotal building blocks for facile access to novel MR emitters featuring narrowband spectra and high efficiency.However,there remains a scarcity of exploration concerning synthetic methods and structural derivations to expand the library of novel BN-MR emitters.Herein,we present the synthesis of a BN-MR emitter,tCz[B−N]N,through a one-pot borylation reaction directed by the amine group,achieving an impressive yield of 94%.The emitter is decorated by incorporating two 3,6-di-tbutylcarbazole(tCz)units into a B−N covalent bond doped BN-MR parent molecule via para-C−π−D and para-N−π−D conjugations.This peripheral decoration strategy enhances the reverse intersystem crossing process and shifts the emission band towards the pure green region,peaking at 526 nm with a narrowband full-width at half maximum(FWHM)of 41 nm.Consequently,organic light emitting diodes(OLEDs)employing this emitter achieved a maximum external quantum efficiency(EQEmax)value of 27.7%,with minimal efficiency roll-off.Even at a practical luminance of 1000 cd·m^(−2),the device maintains a high EQE value of 24.6%.
文摘Lateral oxidation in vertical cavity surface emitting lasers （VCSELs） is described,and its characteristics are investigated.A linear growth law is found for stripe mesas. However, oxide growth （above 435℃ ） follows a nonlinear law for the two geometry mesa structures which we employ in VCSEL. Theoretical analysis indicates that mesa structure geometry influences oxide growth rate at higher temperatures.
文摘High slope efficiency and high power selected oxide-confined 850nm VCSELs grown by MOCVD are reported.The slope efficiency and the threshold current respectively are 0 82mW/mA and 2 59mA with a 9μm diameter oxidation aperture at 25℃.The maximum power of 16mW is obtained at 23mA current bias.The minimum threshold current can be as low as 570μA with a 5μm diameter oxidation aperture at 25℃.The maximum saturated power is 5 5mW.
文摘A 1.3μm low-threshold edge-emitting AlGaInAs multiple-quantum-well(MQW) laser with AlInAs-oxide confinement layers is fabricated.The Al-contained waveguide layers upper and low the active layers are oxidized as current-confined layers using wet-oxidation technique.This structure provides excellent current and optical confinement,resulting in 12.9mA of a low continuous wave threshold current and 0.47W/A of a high slope efficiency of per facet at room temperature for a 5-μm-wide current aperture.Compared with the ridge waveguide laser with the same-width ridge,the threshold current of the AlInAs-oxide confinement laser has decreased by 31.7% and the slope efficiency has increased a little.Both low threshold and high slope efficiency indicate that lateral current confinement can be realized by oxidizing AlInAs waveguide layers.The full width of half maximum angles of the Al-InAs-oxide confinement laser are 21.6° for the horizontal and 36.1° for the vertical,which demonstrate the ability of the AlInAs oxide in preventing the optical field from spreading laterally.
基金the National Natural Science Foundation of China (Grant Nos.61204087, 61306099)the Guangdong Natural Science Foundation (Grant No. S2012040007003)+2 种基金China Postdoctoral Science Foundation (2013M531841)the Fundamental Research Funds for the Central Universities (2014ZM0003, 2014ZM0034, 2014ZM0037, 2014ZZ0028)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20120172120008)
文摘A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,000 cd/m2. A peak color rendering index of 90 and a relatively stable color during a wide range of luminance were obtained. In addition, it was demonstrated that the 4,40,400-tri(9-carbazoyl) triphenylamine host influenced strongly the performance of this WOLED.These results may be beneficial to the design of both material and device architecture for high-performance WOLED.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2006AA03A121)the National Basic Research Program of China(Grant No.2006CB604900)
文摘The reasons for low output power of AlGalnP Light Emitting Diodes （LEDs） have been analysed. LEDs with AlGaInP material have high internal but low external quantum efficiency and much heat generated inside especially at a large injected current which would reduce both the internal and external quantum efficiencies. Two kinds of LEDs with the same active region but different window layers have been fabricated. The new window layer composed of textured 0.5 μm GaP and thin Indium-Tin-Oxide film has shown that low external quantum efficiency （EQE） has serious impaction on the internal quantum efficiency （IQE）, because the carrier distribution will change with the body temperature increasing due to the heat inside, and the test results have shown the evidence of LEDs with lower output power and bigger wavelength red shift.
基金Project supported by the National Natural Science Foundation of China (50872036)
文摘Polycrystalline Gd2(MoO4)3:Dy3+ phosphors have been synthesized by high temperature solid-state reaction method. The phosphors were characterized with X-ray diffractometer, thermogravimetric analysis and different scanning calorimeter, scanning electron microscopy, and photoluminescence spectrofluorimeter. Several peaks at 351, 389, 425, 452, and 472 nm appeared in photoluminescence excitation spectrum, which matched well with the emission of the ultraviolet (UV) and blue-light emitting diode (LED) chips. Upon excitation at 389 nm UV light, intense emissions centered at 484, 575 and 668 nm were attributed to the transitions of 4F9/2→6H15/2, 4F9/2→6H13/2 and 4F9/2→6H11/2 of Dy3+, respectively. The chromaticity coordinates and correlative color temperatures have been calculated and presented in the Commission International de I’Eclairage (CIE) diagrams. The results indicated that Gd1.9(MoO4)3:Dy0.13+ with CIE coordinates of (x=0.38, y=0.41) and the correlative color temperature of 4134 K is a potential candidate for white LEDs.
基金Project supported by the National Basic Research Program of China(Grant Nos.2013CB632804,2011CB301900,and 2012CB3155605)the National Natural Science Foundation of China(Grant Nos.61176015,61210014,51002085,61321004,61307024,and 61176059)the High Technology Research and Development Program of China(Grant No.2012AA050601)
文摘InGaN quantum dot is a promising optoelectronic material, which combines the advantages of low-dimensional and wide-gap semiconductors. The growth of InGaN quantum dots is still not mature, especially the growth by metal--organic- vapor phase epitaxy （MOVPE）, which is challenge due to the lack of, itin-situ monitoring tool. In this paper, we reviewed the development of InGaN quantum dot growth by MOVPE, including our work on growth of near-UV, green, and red InGaN quantum dots. In addition, we also introduced the applications of InGaN quantum dots on visible light emitting diodes.
基金Project supported by the National Key Research and Development Program,China(Grant Nos.2016YFB0401702 and 2017YFE0120400)the National Natural Science Foundation of China(Grant Nos.61875082 and 61405089)+6 种基金the Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting,China(Grant No.2017KSYS007)the Natural Science Foundation of Guangdong,China(Grant No.2017B030306010)the Guangdong Province’s 2018–2019 Key R&D Program:Environmentally Friendly Quantum Dots Luminescent Materials,China(Grant No.2019B010924001)the Shenzhen Innovation Project,China(Grant Nos.JCYJ20160301113356947 and JSGG20170823160757004)the Shenzhen Peacock Team Project,China(Grant No.KQTD2016030111203005)the Shenzhen Key Laboratory for Advanced Quantum Dot Displays and Lighting,China(Grant No.ZDSYS201707281632549)the Tianjin New Materials Science and Technology Key Project,China(Grant No.16ZXCLGX00040)
文摘This paper reviews the recent progress in the synthesis of near-infrared(NIR) lead chalcogenide(PbX;PbX = PbS,PbSe, PbTe) quantum dots(QDs) and their applications in NIR QDs based light emitting diodes(NIR-QLEDs). It summarizes the strategies of how to synthesize high efficiency PbX QDs and how to realize high performance Pb X based NIR-QLEDs.
基金the National"12th Five-year"Science and Technology Support Program of China(No.2011BAE22B03-3)the Project of Chong qing Scientific and Technological Commission(No.CSTC2010AA4048)
文摘A red-emitting phosphor GdNbO4：Eu3＋,Bi3＋ was prepared by a high temperature solid-state reaction technique. The phosphor was characterized by X-ray diffraction （XRD）, particle size analyzer and fluorescence spectrometer. The single phase of GdNbO4：Eu3＋,Bi3＋ was obtained at 1150~C and the average particle diameter was about 2.30 μm. Excitation and emission spectra reveal that the phosphor can be ef- ficiently excited by ultraviolet （UV） light （394 nm） and emit the strong red light of 612 nm due to the Eu3＋ transition of SD0~TF2. The opti- mum content of Eu3＋ doped in the phosphor GdNbOn：Eu3＋ is 20mo1%. The phosphor Gdo.80NbO4：0.20Eu3＋,0.03Bi3＋ shows much stronger photoluminescence intensity and better chromaticity coordinates （x=0.642, 0.352） than GdNbO4：Eu3＋. It is confirmed that Gdo.80NbO4：0.20Eu3＋,0.03Bi3＋ is a potential candidate for near-UV chip-based white light emitting diodes.
基金H.Zeng thanks National Natural Science Foundation of China(61725402,62004101)the Fundamental Research Funds for the Central Universities(30919012107,30920041117)+4 种基金"Ten Thousand Talents Plan"(W03020394)the Six Top Talent Innovation Teams of Jiangsu Province(TDXCL-004)the China Postdoctoral Science Foundation(2020M681600)the Postdoctoral Research Funding Scheme of Jiangsu Province(2020Z124)for financial support.L.Ding thanks the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China(51773045,21772030,51922032,21961160720)for financial support.
文摘White light-emitting diodes(WLEDs),as key infrastructure,play an important role in the field of lighting and display.In the past few decades,many methods were developed to prepare WLEDs.A common strategy is to use blue LEDs to excite yttrium aluminum garnet(YAG)phosphors and generate composite white light,which is now the main technology for commercial lighting.In 2014,Nobel Prize in Physics was awarded to Nakamura et al.for their contribution to blue LEDs[1,2].
文摘lNovel lithium doped tris 8 hydroxylquinoline aluminium(Alq3:Li) layer is deposited between emission layer and electron injection aluminium electrode as an electron injection assistant layer in different organic light emitting diodes(OLED) to lower the electron injection barrier. In these devices, Alq3 is used as emission layer, and a bilayer film of N,N bis (1 naphhyl) N,N diphenyl 1,1 biphenyle 4,4' diamine(NPB) and 4,4,4' tris(3 methyl phenylphenylamino) triphenylamine( m MTDATA) used as hole transport layer(HTL). The electroluminescent performance of devices with different thicknesses of Alq3∶Li shows that the insertion of the lithium doped Alq3 layer can reduce the turn on voltage by at least 2 volts, and the stability of devices with this lithium doped Alq3 layer is improved too. It can also change the efficiency of devices. Compared with an ultra thin lithium fluoride(LiF) layer, Alq3∶Li sheet gives similar effects but higher efficiency and can be much thicker and hence it is easier to control the deposition.
文摘Organic light emitting diodes employing magnesium doped electron acceptor 3, 4, 9, 10 perylenetetracarboxylic dianhydride （Mg：PTCDA） as electron injection layer and silver as cathode were demonstrated. As compared to Mg ： Ag cathode, the combination of the Mg ： PTCDA layer and silver provided enhanced electron injection into tris （8- quinolinolato） aluminium. The device with 1 ： 2 Mg ： PTCDA and Ag showed an increase of about 12% in the maximum current efficiency, mainly due to the improved hole-electron balance, and an increase of about 28% in the maximum power efficiency, as compared to the control device using Mg ： Ag cathode. The properties of Mg ： PTCDA composites were studied as well.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60536030,61036002,60776024,60877035 and 61036009)National High Technology Research and Development Program of China(Grant Nos.2007AA04Z329 and 2007AA04Z254)
文摘A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μm complementary metal-oxide-semiconductor technology. This device is capable of versatile working modes： it can emit visible to near infra-red （NIR） light （the spectrum ranges from 500 nm to 1000 nm） in reverse bias avalanche breakdown mode with working voltage between 8.35 V-12 V and emit NIR light （the spectrum ranges from 900 nm to 1300 nm） in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.
基金supported by the National Natural Science Foundation of China(Grant No.50675130)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(Grant No.2011BAE01B14)the Program for the New Century Excellent Talents in University(Grant No.NCET-07-0535)
文摘This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes （flip chip LEDs） on Si substrates. The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based LED were investigated. In the sequent aging tests, samples were driven with a constant current of 80 mA for hundreds hours at the room temperature. It was found that the electroluminescence （EL） intensity variation had a large correlation to the ultrasonic power, and then to the bonding temperature and force. A high bonding temperature and ultrasonic power and a proper bonding force improved the EL intensity significantly. It was contributed to a strong atom inter-diffusion forming a stable joint at the bonding interface, The temperature fluctuation in the aging test was the main factor to generate a high inner stress forming delamination at the interface between the chip and Au bump. As a result, delamination had retarded the photons to emit out of the LED packaging and decay its EL intensity.
基金supported by the National Natural Science Foundation of China(Grant Nos.61136003 and 61275041)the Project of Science and TechnologyCommission of Shanghai Municipality,China(Grant No.14XD1401800)
文摘We characterized the 6,12-bis{[N-（3,4-dimethylphenyl）-N-（2,4,5-trimethylphenyl）]amino} chrysene （BmPAC）, which has been proven to be a blue fluorescent emission with high EL efficiency. The blue fluorescent device exhibits good performance with an external quantum efficiency of 5.8% and current efficiency of 8.9 cd/A, respectively. Using BmPAC, we also demonstrate a hybrid phosphorescence/fluorescence white organic light-emitting device （WOLED） with high efficiency of 36.3 cd/A. In order to improve the relative intensity of blue light, we plus a blue light-emitting layer （BEML） in front of the orange light emitting layer （YEML） to take advantage of the excess singlet excitons. With the new emitting layer of BEML/YEML/BEML, we demonstrate the fluorescence/phosphorescence/fluorescence WOLED exhibits good performance with a current efficiency of 47 cd/A and an enhanced relative intensity of blue light.
