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
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
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
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
With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><s...With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><span> </span><span>(50 μmol·m</span><sup><span style="vertical-align:super;">-2</span></sup><span>·s</span><sup><span style="vertical-align:super;">-1</span></sup><span>) including white LED light</span><span> </span><span>(WL), blue monochromatic light (B,</span><span> </span><span>465 nm), and red monochromatic light (R, 650 nm) were carried out to investigate their effects on seed germination, physiological and biochemical parameters, sex differentiation and photosynthetic characteristics of bitter gourd. The results showed that compared to the WL treatment, the R treatment significantly promoted seed germination, seedling height elongation and soluble sugar content, the B treatment significantly increased seedling stem diameter, reducing sugar content and soluble protein content, the R and B treatments both significantly reduced sucrose content, but their POD activity showed no significant difference. Compared with the R treatment, the B treatment significantly increased the total female flower number and female flower nod ratio in 30 nods of main stems. The study of photosynthetic characteristics found that the R and B treatments could effectively increase the </span><span>stomata</span><span>l conductance (GS) of leaves, significantly improved the net photosynthetic rate</span><span> </span><span>(Pn) compared to the WL treatment, and the effect of the B treatment was better. Compared to the R and WL treatments, the B treatment increased the maximum photosynthetic rate (P</span><sub><span style="vertical-align:sub;">max</span></sub><span>),</span><span> </span><span>apparent quantum efficiency</span><span> </span><span>(AQE) and light saturation point</span><span> </span><span>(LSP), and reduced the dark respiration rate (Rd) and light compensation point</span><span> </span><span>(LCP) of the leaves. Fit light response curves showed that the adaptability and utilization of weak light in bitter gourd were middle or below, but it showed higher adaptability and utilization of strong light. Thus, it suggests that </span><i><span>Momordica charantia</span></i><span> is a typical sun plan with lower Rd. In summary, it is concluded that blue light has a positive effect on the seed germination, seedling growth, sex differentiation and improving the photosynthetic performance, and this will lay the foundation for artificially regulating optimum photosynthesis using specific LEDs wavelength, and help to elucidate the relationship how light quality influences the sex differentiation of plant.</span>展开更多
Organic field-effect transistors(OFETs) based on organic micro-/nanocrystals have been widely reported with charge carrier mobility exceeding 1.0 cm^2V^(-1)s^(-1), demonstrating great potential for high-performance, l...Organic field-effect transistors(OFETs) based on organic micro-/nanocrystals have been widely reported with charge carrier mobility exceeding 1.0 cm^2V^(-1)s^(-1), demonstrating great potential for high-performance, low-cost organic electronic applications. However, fabrication of large-area organic micro-/nanocrystal arrays with consistent crystal growth direction has posed a significant technical challenge. Here, we describe a solution-processed dip-coating technique to grow large-area, aligned 9,10-bis(phenylethynyl) anthracene(BPEA) and 6,13-bis(triisopropylsilylethynyl) pentacene(TIPSPEN) single-crystalline nanoribbon arrays. The method is scalable to a 5 9 10 cm^2 wafer substrate, with around 60% of the wafer surface covered by aligned crystals. The quality of crystals can be easily controlled by tuning the dip-coating speed. Furthermore, OFETs based on well-aligned BPEA and TIPS-PEN single-crystalline nanoribbons were constructed.By optimizing channel lengths and using appropriate metallic electrodes, the BPEA and TIPS-PEN-based OFETs showed hole mobility exceeding 2.0 cm^2V^(-1)s^(-1)(average mobility 1.2 cm^2V^(-1)s^(-1)) and 3.0 cm^2V^(-1)s^(-1)(average mobility2.0 cm^2V^(-1)s^(-1)), respectively. They both have a high on/off ratio(I_(on)/I_(off))>10~9. The performance can well satisfy the requirements for light-emitting diodes driving.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
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
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
Sr2SiO4:xEu^2+ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu^2+ phosphor manipulated by Eu^2+ concentration was studied. The phase transited from β to α...Sr2SiO4:xEu^2+ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu^2+ phosphor manipulated by Eu^2+ concentration was studied. The phase transited from β to α' in Sr2SiO4:xEu^2+ phosphor with increasing europium concentration. The single β phase was formed as x≤005 and changed α' phase when x〉0.01. The emission spectrum of the β-Sr2SiO4:Eu^2+ phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4:Eu^2+ phosphors were fabricated. The luminous efficiency (15.7lm/W) was higher than α'-Sr2SiO4:Eu^2+ phosphor white LED.展开更多
Perovskite light emitting diodes(PeLEDs)have attracted considerable research attention because of their external quantum efficiency(EQE)of>20%and have potential scope for further improvement.However,compared to red...Perovskite light emitting diodes(PeLEDs)have attracted considerable research attention because of their external quantum efficiency(EQE)of>20%and have potential scope for further improvement.However,compared to red and green PeLEDs,blue PeLEDs have not been extensively investigated,which limits their commercial applications in the fields of luminance and full-color displays.In this review,blue-PeLED-related research is categorized by the composition of perovskite.The main challenges and corresponding optimization strategies for perovskite films are summarized.Next,the novel strategies for the design of device structures of blue PeLEDs are reviewed from the perspective of transport layers and interfacial layers.Accordingly,future directions for blue PeLEDs are discussed.This review can be a guideline for optimizing perovskite film and device structure of blue PeLEDs,thereby enhancing their development and application scope.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
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
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
Solution-processed metal halide perovskites (MHPs) have received significant interest for cost-effective, high-performance optoelectronic devices. In addition to the great successes in photovoltaics, their excellent l...Solution-processed metal halide perovskites (MHPs) have received significant interest for cost-effective, high-performance optoelectronic devices. In addition to the great successes in photovoltaics, their excellent luminescence and charge transport properties also make them promising for light emitting diodes (LEDs). To achieve high-efficiency perovskite LEDs (PeLEDs), extensive efforts have been carried out to enhance radiative recombination rates by confining the electrons and holes. In addition to enhancing radiative recombination rates, it is equally important to decrease the non-radiative recombination for improving the device performance. Passivation of the defects could be an efficient way for reducing the non-radiative recombination.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
The well crystalline YAG:Ce^3+ phosphor was synthesized by sold-state method, and the temperature dependence of excitation and emission spectra of YAG:Ce^3+ phosphor were investigated in the temperature range from...The well crystalline YAG:Ce^3+ phosphor was synthesized by sold-state method, and the temperature dependence of excitation and emission spectra of YAG:Ce^3+ phosphor were investigated in the temperature range from room temperature to 573 K. With temperature increasing, it was noted that the emission intensity of as-repared phosphors decreased considerably more rapidly when pumped by 460 nm than by 340 nm. The temperature-intensity curves under different excitation wavelengths were obtained using an Arrhenius function, and the corresponding activation energies were also obtained respectively. Thus, the experimental phenomenon was discussed in terms of nonradiative decay rate. The effects of as-prepared phosphors on the performance of the white LED with changing temperature were also studied.展开更多
In this paper, the Sr3Y2 (BO3)4 :Eu^3+ phosphor was synthesized by high temperature solid-state reaction method and the luminescence characteristics were investigated. The emission spectrum exhibits one strong red...In this paper, the Sr3Y2 (BO3)4 :Eu^3+ phosphor was synthesized by high temperature solid-state reaction method and the luminescence characteristics were investigated. The emission spectrum exhibits one strong red emission at 613 nm corresponding to the electric dipole 5^Do-7^F2 transition of Eu^3+ under 365 nm excitation, this is because Eu^3+ substituted for Y^3+ occupied the non-centrosymmetric position in the crystal structure of Sr3Y2(BO3)4. The excitation spectrum indicates that the phosphor can be effectively excited by ultraviolet (254 nm, 365 nm and 400 nm) and blue (470 nm) light. The effect of Eu^3+ concentration on the red emission of Sr3Y2(BO3)4 :Eu^3+ was measured, the result shows that the emission intensities increase with increasing Eu^3+ concentration, then decrease. The Commission Internationale del'Eclairage chromaticity (x, y) of Sr3Y2(BO3)4 :Eu^3+ phosphor is (0.640, 0.355) at 15 mol% Eu^3+.展开更多
A lateral current regulator diode (CRD) with field plates is proposed and experimentally demonstrated. The proposed CFtD is based on the junction field-effect transistor (JFET) structure. A cathode field plate is ...A lateral current regulator diode (CRD) with field plates is proposed and experimentally demonstrated. The proposed CFtD is based on the junction field-effect transistor (JFET) structure. A cathode field plate is adopted to alleviate the channel-length modulation effect and to improve the saturated I-V characteristics. An anode field plate is induced to achieve a high breakdown voltage VB of the CRD. The influence of the key device parameters on the I-V characteristics of the lateral CRD are discussed. Experimental results show that the proposed CRD presents good I-V characteristics with a high VB about 180 V and a low knee voltage (Vk) below 3 V. Furthermore, the proposed CRD has a negative temperature coefficient. The well characteristic of the proposed CRD makes it a cost-effective solution for light-emitting-diode lighting.展开更多
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].
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.
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.
文摘With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><span> </span><span>(50 μmol·m</span><sup><span style="vertical-align:super;">-2</span></sup><span>·s</span><sup><span style="vertical-align:super;">-1</span></sup><span>) including white LED light</span><span> </span><span>(WL), blue monochromatic light (B,</span><span> </span><span>465 nm), and red monochromatic light (R, 650 nm) were carried out to investigate their effects on seed germination, physiological and biochemical parameters, sex differentiation and photosynthetic characteristics of bitter gourd. The results showed that compared to the WL treatment, the R treatment significantly promoted seed germination, seedling height elongation and soluble sugar content, the B treatment significantly increased seedling stem diameter, reducing sugar content and soluble protein content, the R and B treatments both significantly reduced sucrose content, but their POD activity showed no significant difference. Compared with the R treatment, the B treatment significantly increased the total female flower number and female flower nod ratio in 30 nods of main stems. The study of photosynthetic characteristics found that the R and B treatments could effectively increase the </span><span>stomata</span><span>l conductance (GS) of leaves, significantly improved the net photosynthetic rate</span><span> </span><span>(Pn) compared to the WL treatment, and the effect of the B treatment was better. Compared to the R and WL treatments, the B treatment increased the maximum photosynthetic rate (P</span><sub><span style="vertical-align:sub;">max</span></sub><span>),</span><span> </span><span>apparent quantum efficiency</span><span> </span><span>(AQE) and light saturation point</span><span> </span><span>(LSP), and reduced the dark respiration rate (Rd) and light compensation point</span><span> </span><span>(LCP) of the leaves. Fit light response curves showed that the adaptability and utilization of weak light in bitter gourd were middle or below, but it showed higher adaptability and utilization of strong light. Thus, it suggests that </span><i><span>Momordica charantia</span></i><span> is a typical sun plan with lower Rd. In summary, it is concluded that blue light has a positive effect on the seed germination, seedling growth, sex differentiation and improving the photosynthetic performance, and this will lay the foundation for artificially regulating optimum photosynthesis using specific LEDs wavelength, and help to elucidate the relationship how light quality influences the sex differentiation of plant.</span>
基金supported by the National Basic Research Program of China(2013CB933500)National Natural Science Foundation of China(Grant Nos.61422403,51672180,51622306,21673151)+2 种基金Qing Lan ProjectCollaborative Innovation Center of Suzhou Nano Science and Technology(NANO-CIC)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Organic field-effect transistors(OFETs) based on organic micro-/nanocrystals have been widely reported with charge carrier mobility exceeding 1.0 cm^2V^(-1)s^(-1), demonstrating great potential for high-performance, low-cost organic electronic applications. However, fabrication of large-area organic micro-/nanocrystal arrays with consistent crystal growth direction has posed a significant technical challenge. Here, we describe a solution-processed dip-coating technique to grow large-area, aligned 9,10-bis(phenylethynyl) anthracene(BPEA) and 6,13-bis(triisopropylsilylethynyl) pentacene(TIPSPEN) single-crystalline nanoribbon arrays. The method is scalable to a 5 9 10 cm^2 wafer substrate, with around 60% of the wafer surface covered by aligned crystals. The quality of crystals can be easily controlled by tuning the dip-coating speed. Furthermore, OFETs based on well-aligned BPEA and TIPS-PEN single-crystalline nanoribbons were constructed.By optimizing channel lengths and using appropriate metallic electrodes, the BPEA and TIPS-PEN-based OFETs showed hole mobility exceeding 2.0 cm^2V^(-1)s^(-1)(average mobility 1.2 cm^2V^(-1)s^(-1)) and 3.0 cm^2V^(-1)s^(-1)(average mobility2.0 cm^2V^(-1)s^(-1)), respectively. They both have a high on/off ratio(I_(on)/I_(off))>10~9. The performance can well satisfy the requirements for light-emitting diodes driving.
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 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the Ministry of Science and Technology (MOST) of China (2006AA03A138)the National Natural Science Foundation of China (10774141, 10574128)
文摘Sr2SiO4:xEu^2+ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu^2+ phosphor manipulated by Eu^2+ concentration was studied. The phase transited from β to α' in Sr2SiO4:xEu^2+ phosphor with increasing europium concentration. The single β phase was formed as x≤005 and changed α' phase when x〉0.01. The emission spectrum of the β-Sr2SiO4:Eu^2+ phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4:Eu^2+ phosphors were fabricated. The luminous efficiency (15.7lm/W) was higher than α'-Sr2SiO4:Eu^2+ phosphor white LED.
基金This work was supported by the National Natural Science Foundation of China(51775199,51735004)Natural Science Foundation of Guangdong Province(2018B030306008)the Fundamental Research Funds for the Central Universities.
文摘Perovskite light emitting diodes(PeLEDs)have attracted considerable research attention because of their external quantum efficiency(EQE)of>20%and have potential scope for further improvement.However,compared to red and green PeLEDs,blue PeLEDs have not been extensively investigated,which limits their commercial applications in the fields of luminance and full-color displays.In this review,blue-PeLED-related research is categorized by the composition of perovskite.The main challenges and corresponding optimization strategies for perovskite films are summarized.Next,the novel strategies for the design of device structures of blue PeLEDs are reviewed from the perspective of transport layers and interfacial layers.Accordingly,future directions for blue PeLEDs are discussed.This review can be a guideline for optimizing perovskite film and device structure of blue PeLEDs,thereby enhancing their development and application scope.
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.
文摘Solution-processed metal halide perovskites (MHPs) have received significant interest for cost-effective, high-performance optoelectronic devices. In addition to the great successes in photovoltaics, their excellent luminescence and charge transport properties also make them promising for light emitting diodes (LEDs). To achieve high-efficiency perovskite LEDs (PeLEDs), extensive efforts have been carried out to enhance radiative recombination rates by confining the electrons and holes. In addition to enhancing radiative recombination rates, it is equally important to decrease the non-radiative recombination for improving the device performance. Passivation of the defects could be an efficient way for reducing the non-radiative recombination.
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the Key Technologies R&D Program of Shandong Province (2006gg2201014)Tianjin Natural Science Foundation (07JCYBJC06400)Tianjin Education Committee Science and Technology Development Foundation
文摘The well crystalline YAG:Ce^3+ phosphor was synthesized by sold-state method, and the temperature dependence of excitation and emission spectra of YAG:Ce^3+ phosphor were investigated in the temperature range from room temperature to 573 K. With temperature increasing, it was noted that the emission intensity of as-repared phosphors decreased considerably more rapidly when pumped by 460 nm than by 340 nm. The temperature-intensity curves under different excitation wavelengths were obtained using an Arrhenius function, and the corresponding activation energies were also obtained respectively. Thus, the experimental phenomenon was discussed in terms of nonradiative decay rate. The effects of as-prepared phosphors on the performance of the white LED with changing temperature were also studied.
基金supported by Hebei Provincial Technology Development Foundation of China (Grant No 51215103b)Science Foundation of Hebei University, China (Grant No 2006Q06)
文摘In this paper, the Sr3Y2 (BO3)4 :Eu^3+ phosphor was synthesized by high temperature solid-state reaction method and the luminescence characteristics were investigated. The emission spectrum exhibits one strong red emission at 613 nm corresponding to the electric dipole 5^Do-7^F2 transition of Eu^3+ under 365 nm excitation, this is because Eu^3+ substituted for Y^3+ occupied the non-centrosymmetric position in the crystal structure of Sr3Y2(BO3)4. The excitation spectrum indicates that the phosphor can be effectively excited by ultraviolet (254 nm, 365 nm and 400 nm) and blue (470 nm) light. The effect of Eu^3+ concentration on the red emission of Sr3Y2(BO3)4 :Eu^3+ was measured, the result shows that the emission intensities increase with increasing Eu^3+ concentration, then decrease. The Commission Internationale del'Eclairage chromaticity (x, y) of Sr3Y2(BO3)4 :Eu^3+ phosphor is (0.640, 0.355) at 15 mol% Eu^3+.
基金Supported by the National Natural Science Foundation of China under Grant No 61376080
文摘A lateral current regulator diode (CRD) with field plates is proposed and experimentally demonstrated. The proposed CFtD is based on the junction field-effect transistor (JFET) structure. A cathode field plate is adopted to alleviate the channel-length modulation effect and to improve the saturated I-V characteristics. An anode field plate is induced to achieve a high breakdown voltage VB of the CRD. The influence of the key device parameters on the I-V characteristics of the lateral CRD are discussed. Experimental results show that the proposed CRD presents good I-V characteristics with a high VB about 180 V and a low knee voltage (Vk) below 3 V. Furthermore, the proposed CRD has a negative temperature coefficient. The well characteristic of the proposed CRD makes it a cost-effective solution for light-emitting-diode lighting.