According to the second law of thermodynamics,spontaneous chemical processes will ultimately reach the equilibrium state with the lowest energy.However,in biological systems,there are numerous highenergy states far fr...According to the second law of thermodynamics,spontaneous chemical processes will ultimately reach the equilibrium state with the lowest energy.However,in biological systems,there are numerous highenergy states far from equilibrium.One typical example is the transmembrane ion-concentration gradient,which plays crucial roles in maintaining homeostasis,regulating cell volume,and enabling cell signaling.Transmembrane ion-concentration gradient is achieved by an active transport process that requires the input of energy and the action of pump proteins.Replicating this process with synthetic supramolecular systems is particularly challenging,requiring both the input of energy and very specific,spatiotemporal control over ion uptake and release.In nature,pump proteins,such as protein-based ion channels,have evolved highly intricate architectures to perform this function.In contrast,Aprahamian and coworkers recently developed a much simpler smallmolecule system that functions as a molecular ion pump,utilizing light energy to pump chloride ions across a hydrophobic barrier against the concentration gradient[1].展开更多
A novel phase change heat sink was fabricated for packaging cooling of high power light emitting diode （LED）. 3D structures as enhanced boiling structure in the evaporation surface were composed of a spiral micro-gr...A novel phase change heat sink was fabricated for packaging cooling of high power light emitting diode （LED）. 3D structures as enhanced boiling structure in the evaporation surface were composed of a spiral micro-groove along circumferential direction and radial micro-grooves which were processed by ploughing-extrusion （P-E） and stamping, respectively. Meanwhile, the cycle power of refrigerant was supplied by wick of sintered copper powder on internal surface of phase change heat sink. Operational characteristics were tested under different heat loads and refrigerants. The experimental results show that phase change heat sink is provided with a good heat transfer capability and the temperature of phase change heat sink reaches 86.8 ℃ under input power of 10 W LED at ambient temperature of 20 ℃.展开更多
Boiling structures on evaporation surface of red copper sheet with a diameter （D） of 10 mm and a wall thickness （h） of 1 mm were processed by the ploughing-extrusion （P-E） processing method, which is one part of...Boiling structures on evaporation surface of red copper sheet with a diameter （D） of 10 mm and a wall thickness （h） of 1 mm were processed by the ploughing-extrusion （P-E） processing method, which is one part of the phase-change heat sink for high power （HP） light emitting diode （LED）. The experimental results show that two different structures of rectangular- and triangular-shaped micro-grooves are formed in P-E process. When P-E depth （ap）, interval of helical grooves （dp） and rotation speed （n） are 0.12 ram, 0.2 mm and 100 r/min, respectively, the boiling structures of triangular-shaped grooves with the fin height of 0.15 mm that has good evaporation performance are obtained. The shapes of the boiling structures are restricted by dp and ap, and dp is determined by n and amount of feed （f）. The ploughing speed has an important influence on the formation of groove structure in P-E process.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
Nanostructured TiO2 with differentiate morphologies has attracted tremendous attention due to its wide band-gap nature as well as outstanding optical and electric properties for solar-driven light-toelectricity conver...Nanostructured TiO2 with differentiate morphologies has attracted tremendous attention due to its wide band-gap nature as well as outstanding optical and electric properties for solar-driven light-toelectricity conversion application. Layered-stacking TiO2 film such as double-layer, tri-layer, quadrupleor quintuplicate-layer, is highly desirable to the design of high-performance semiconductor material photoanodes and the development of advanced photovoltaic devices. In this minireview, we will summarize the recent progress and achievements on proof-of-concept of layered-stacking TiO2 films（LTFs） for solar cells with emphasis on the tailored properties and synergistic functionalization of LTFs, such as optimized sensitizer adsorption, broadened light confinement as well as facilitated electron transport characteristics.Various demonstrations of LTFs photovoltaic systems provide lots of possibilities and flexibilities for more efficient solar energy utilization that a wide variety of TiO2 with distinguished morphologies can be integrated into differently structured photoanodes with synergistic and complementary advantages. This key structure engineering technology will also pave the way for the development of next generation state-ofthe-art electronics and optoelectronics. Finally, from our point of view, we conclude the future research interest and efforts for constructing more efficient LTFs as photoelectrode, which will be highly warranted to advance the solar energy conversion process.展开更多
By using the designed photonic crystal fiber filled with argon gas, the effect of gas pressure on modulation instability（MI） gain is analyzed in detail. The MI gain bandwidth increases gradually as the argon gas pre...By using the designed photonic crystal fiber filled with argon gas, the effect of gas pressure on modulation instability（MI） gain is analyzed in detail. The MI gain bandwidth increases gradually as the argon gas pressure rises from 1 P0 to 400 P0（P0 is one standard atmosphere）, while its gain amplitude slightly decreases. Moreover, the increase of the incident light power also results in the increase of MI gain bandwidth in the Stokes or anti-Stokes region when the incident power increases from 1 W to 200 W. Making use of the optimal parameters including the higher argon gas pressure（400 P0） and the incident light power（200 W）, we finally obtain a 100 nm broadband MI gain. These results indicate that controlling the MI gain characteristic by changing the argon gas pressure in PCF is an effective way when the incident light source is not easy to satisfy the requirement of practical application. This method of controlling MI gain can be used in optical communication and laser shaping.展开更多
Micro/nanorobots based on immune cells show great potential for addressing challenging biological and biomedical conditions.However,their powerful innate immune functions,particularly the phagocytosis capabilities,rem...Micro/nanorobots based on immune cells show great potential for addressing challenging biological and biomedical conditions.However,their powerful innate immune functions,particularly the phagocytosis capabilities,remain a big challenge to fully leverage with the current designs of immune cell-based microrobots.Herein,we report a lightpowered phagocytic macrophage microrobot(phagobot),which is capable of robotic navigation toward specific foreign bio-threats and executing precise phagocytosis of these targeted entities under light control.Without genetic modification or nanoengineering of macrophages,the phagobot’s“wake-up”program is achieved through direct activation of a resting-state macrophage by a tightly focused near-infrared(NIR)light beam.The phagobot exhibits robotic steering and directional navigation controlled by optical manipulation of the extended pseudopodia within the activated macrophage.It can further execute targeted phagocytic clearance tasks via engulfing various foreign bio-threats,including nanoplastics,microbials,and cancer cell debris.Notably,the phagobot can be constructed in a living larval zebrafish through optical activation and manipulation of the endogenous macrophage,which also exhibits controllable navigation and targeted phagocytic capabilities in vivo.With the intrinsic immune functions of macrophages,our light-powered phagobot represents a novel form of intelligent immune cell-based microrobots,holding many new possibilities for precise immune regulation and treatment for immune-related diseases.展开更多
A micropump induces the flow of its surrounding fluids and is extremely promising in a variety of applications such as chemical sensing or mass transportation. However, it is still challenging to manipulate its pumpin...A micropump induces the flow of its surrounding fluids and is extremely promising in a variety of applications such as chemical sensing or mass transportation. However, it is still challenging to manipulate its pumping direction. In this stud~ we examine a binary micropump based on perovskite and poly[（2-methoxy-5-ethylhexyloxy）-1,4-phenylenevinylene] （MEHPPV）. The micropump is operational under the influence of light. Light exhibits significant versatility in controlling the pumping phenomenon of the micropump. It governs the start and stop and also regulates the velocity and directions. The direction control signifies immense opportunities for the development of micropumps with unprecedented pumping behaviors and functions （such as heartbeat-like pumping, rectification, and amplification）. This makes them potentially useful in various fields. Hence, it is expected that the micropump reported in the current study could act as a key step towards the further development of more sophisticated micropumps for diverse applications.展开更多
In order to promote the light output powers of GaN-based light emitting diodes (LEDs), two kinds of novel corrosive liquidshave been developed in this paper to roughen the surface of the indium tin oxide (ITO) current...In order to promote the light output powers of GaN-based light emitting diodes (LEDs), two kinds of novel corrosive liquidshave been developed in this paper to roughen the surface of the indium tin oxide (ITO) current spreading layer of LEDs. As aresult, the textured transparent ITO layer greatly enhanced the external quantum efficiency of the LEDs. Provided that a wafersample was dipped in a kind of corrosive liquid developed by us for only about 60 s, the light output powers of the LEDs canbe promoted by 24.7%, compared with conventional GaN-based LEDs. It is obvious that the presented method is simple, rapidand cost-effective.展开更多
Appropriate and adequate lighting at select locations on roadways is essential for roadway safety. As the lighting technologies advance, many Wpes of new lighting devices have been developed for roadway lightings. The...Appropriate and adequate lighting at select locations on roadways is essential for roadway safety. As the lighting technologies advance, many Wpes of new lighting devices have been developed for roadway lightings. The most promising new lighting technologies for roadway lighting include light emitting diode, induction, plasma, and metal halide lighting systems. A study was conducted to compare the new systems with the conventional high pressure sodium systems that are currently used on the Indiana roadway systems. In this study, the engineering issues, were analyzed such as illuminance, color rendering, power usage, cost effectiveness, and approval procedures for new roadway lighting systems. This paper, however, presents only the study findings related to cost effectiveness of the evaluated roadway lighting systems. Illustrated in this paper are the main features of the roadway lighting systems under evaluations, installations of the new lighting systems, measurements of power consumptions, and life cycle cost analyses of the lighting systems. Through this study, experience and knowledge have been obtained on the installations, power measurements, and cost effectiveness of the new types of the roadway lighting devices. The actual power values of various luminaires were obtained by measuring the electric current with a multi-meter. It was found that the differences between the rated and measured power values could be significant. The results of the life cycle cost analysis indicate that the lower life cycle costs of some of the alternative lighting devices are attributed to their relatively lower electricity usages and longer lamp/emitter replacement cycles.展开更多
This paper reports a new method of fabricating AlGaInP-based nanorod light emitting diodes（LEDs） by using self-assembly metal layer nanomasks and inductively coupled plasma.Light-power measurements indicate that the...This paper reports a new method of fabricating AlGaInP-based nanorod light emitting diodes（LEDs） by using self-assembly metal layer nanomasks and inductively coupled plasma.Light-power measurements indicate that the scattering of photons considerably enhances the probability of escaping from the nanorod LEDs.The light-intensity of the nanorod LED is increased by 34%for a thin GaP window layer,and by 17%for an 8μm GaP window layer.The light-power of the nanorod LED is increased by 25%and 13%,respectively.展开更多
The effect of patterned sapphire substrate（PSS） on the top-surface（P-Ga N-surface） and the bottomsurface（sapphire-surface） of the light output power（LOP） of Ga N-based LEDs was investigated, in order to study ...The effect of patterned sapphire substrate（PSS） on the top-surface（P-Ga N-surface） and the bottomsurface（sapphire-surface） of the light output power（LOP） of Ga N-based LEDs was investigated, in order to study the changes in reflection and transmission of the Ga N-sapphire interface. Experimental research and computer simulations were combined to reveal a great enhancement in LOP from either the top or bottom surface of Ga N-based LEDs, which are prepared on patterned sapphire substrates（PSS-LEDs）. Furthermore, the results were compared to those of the conventional LEDs prepared on the planar sapphire substrates（CSS-LEDs）. A detailed theoretical analysis was also presented to further support the explanation for the increase in both the effective reflection and transmission of PSS-Ga N interface layers and to explain the causes of increased LOP values. Moreover, the bottom-surface of the PSS-LED chip shows slightly increased light output performance when compared to that of the top-surface. Therefore, the light extraction efficiency（LEE） can be further enhanced by integrating the method of PSS and flip-chip structure design.展开更多
In order to determine the environmental effects on the luminescence properties of a phosphor layer for high-power light emitting diodes, a high humidity and temperature test （85℃/85%RH） and a thermal aging test （8...In order to determine the environmental effects on the luminescence properties of a phosphor layer for high-power light emitting diodes, a high humidity and temperature test （85℃/85%RH） and a thermal aging test （85℃） were performed on silicone/YAG phosphor composites. The luminescence properties of silicone/phosphor composites are monitored by a fluorescence spectrometer. The results show that high temperature could result in an increase in conversion efficiency of composites during the early aging stage and red shift of YAG phosphor; and high humidity could result in a significant decrease in conversion efficiency of composites while having a small influence upon the optimal excitation wavelength of the YAG phosphor.展开更多
基金financial supports of National Natural Science Foundation of China(22171226)Natural Science Basic Research Program of Shaanxi(2022JC-06).
文摘According to the second law of thermodynamics,spontaneous chemical processes will ultimately reach the equilibrium state with the lowest energy.However,in biological systems,there are numerous highenergy states far from equilibrium.One typical example is the transmembrane ion-concentration gradient,which plays crucial roles in maintaining homeostasis,regulating cell volume,and enabling cell signaling.Transmembrane ion-concentration gradient is achieved by an active transport process that requires the input of energy and the action of pump proteins.Replicating this process with synthetic supramolecular systems is particularly challenging,requiring both the input of energy and very specific,spatiotemporal control over ion uptake and release.In nature,pump proteins,such as protein-based ion channels,have evolved highly intricate architectures to perform this function.In contrast,Aprahamian and coworkers recently developed a much simpler smallmolecule system that functions as a molecular ion pump,utilizing light energy to pump chloride ions across a hydrophobic barrier against the concentration gradient[1].
基金Projects(50436010,50930005)supported by the National Natural Science Foundation of ChinaProject(U0834002)supported by the Joint Fund of NSFC-Guangdong of China
文摘A novel phase change heat sink was fabricated for packaging cooling of high power light emitting diode （LED）. 3D structures as enhanced boiling structure in the evaporation surface were composed of a spiral micro-groove along circumferential direction and radial micro-grooves which were processed by ploughing-extrusion （P-E） and stamping, respectively. Meanwhile, the cycle power of refrigerant was supplied by wick of sintered copper powder on internal surface of phase change heat sink. Operational characteristics were tested under different heat loads and refrigerants. The experimental results show that phase change heat sink is provided with a good heat transfer capability and the temperature of phase change heat sink reaches 86.8 ℃ under input power of 10 W LED at ambient temperature of 20 ℃.
基金Projects(50436010, 50675070) supported by the National Natural Science Foundation of China Project(07118064) supported by the Natural Science Foundation of Guangdong Province, China+1 种基金 Project(U0834002) supported by the Joint Fund of NSFC-Guangdong of ChinaProjects(SY200806300289A, JSA200903190981A) supported by Shenzhen Scientific Program, China
文摘Boiling structures on evaporation surface of red copper sheet with a diameter （D） of 10 mm and a wall thickness （h） of 1 mm were processed by the ploughing-extrusion （P-E） processing method, which is one part of the phase-change heat sink for high power （HP） light emitting diode （LED）. The experimental results show that two different structures of rectangular- and triangular-shaped micro-grooves are formed in P-E process. When P-E depth （ap）, interval of helical grooves （dp） and rotation speed （n） are 0.12 ram, 0.2 mm and 100 r/min, respectively, the boiling structures of triangular-shaped grooves with the fin height of 0.15 mm that has good evaporation performance are obtained. The shapes of the boiling structures are restricted by dp and ap, and dp is determined by n and amount of feed （f）. The ploughing speed has an important influence on the formation of groove structure in P-E process.
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the financial supports from the NSFC(51472274)the GDUPS(2016)+2 种基金the program of Guangzhou Science and Technology Project(201504010031)the NSF of Guangdong Province(S2013030013474)the Fundamental Research Funds for the Central Universities
文摘Nanostructured TiO2 with differentiate morphologies has attracted tremendous attention due to its wide band-gap nature as well as outstanding optical and electric properties for solar-driven light-toelectricity conversion application. Layered-stacking TiO2 film such as double-layer, tri-layer, quadrupleor quintuplicate-layer, is highly desirable to the design of high-performance semiconductor material photoanodes and the development of advanced photovoltaic devices. In this minireview, we will summarize the recent progress and achievements on proof-of-concept of layered-stacking TiO2 films（LTFs） for solar cells with emphasis on the tailored properties and synergistic functionalization of LTFs, such as optimized sensitizer adsorption, broadened light confinement as well as facilitated electron transport characteristics.Various demonstrations of LTFs photovoltaic systems provide lots of possibilities and flexibilities for more efficient solar energy utilization that a wide variety of TiO2 with distinguished morphologies can be integrated into differently structured photoanodes with synergistic and complementary advantages. This key structure engineering technology will also pave the way for the development of next generation state-ofthe-art electronics and optoelectronics. Finally, from our point of view, we conclude the future research interest and efforts for constructing more efficient LTFs as photoelectrode, which will be highly warranted to advance the solar energy conversion process.
基金Project supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY15F050010)the National Natural Science Foundation of China(Grant Nos.11604296,11404286,and 61727821)
文摘By using the designed photonic crystal fiber filled with argon gas, the effect of gas pressure on modulation instability（MI） gain is analyzed in detail. The MI gain bandwidth increases gradually as the argon gas pressure rises from 1 P0 to 400 P0（P0 is one standard atmosphere）, while its gain amplitude slightly decreases. Moreover, the increase of the incident light power also results in the increase of MI gain bandwidth in the Stokes or anti-Stokes region when the incident power increases from 1 W to 200 W. Making use of the optimal parameters including the higher argon gas pressure（400 P0） and the incident light power（200 W）, we finally obtain a 100 nm broadband MI gain. These results indicate that controlling the MI gain characteristic by changing the argon gas pressure in PCF is an effective way when the incident light source is not easy to satisfy the requirement of practical application. This method of controlling MI gain can be used in optical communication and laser shaping.
基金the National Natural Science Foundation of China(12374286,32271405,and 12204196)Guangdong Basic and Applied Basic Research Foundation(2024A1515012514,2022B1515120012)+1 种基金Science and Technology Program of Guangzhou(2024A04J6319)the Fundamental Research Funds for the Central Universities(21623112,21624217).
文摘Micro/nanorobots based on immune cells show great potential for addressing challenging biological and biomedical conditions.However,their powerful innate immune functions,particularly the phagocytosis capabilities,remain a big challenge to fully leverage with the current designs of immune cell-based microrobots.Herein,we report a lightpowered phagocytic macrophage microrobot(phagobot),which is capable of robotic navigation toward specific foreign bio-threats and executing precise phagocytosis of these targeted entities under light control.Without genetic modification or nanoengineering of macrophages,the phagobot’s“wake-up”program is achieved through direct activation of a resting-state macrophage by a tightly focused near-infrared(NIR)light beam.The phagobot exhibits robotic steering and directional navigation controlled by optical manipulation of the extended pseudopodia within the activated macrophage.It can further execute targeted phagocytic clearance tasks via engulfing various foreign bio-threats,including nanoplastics,microbials,and cancer cell debris.Notably,the phagobot can be constructed in a living larval zebrafish through optical activation and manipulation of the endogenous macrophage,which also exhibits controllable navigation and targeted phagocytic capabilities in vivo.With the intrinsic immune functions of macrophages,our light-powered phagobot represents a novel form of intelligent immune cell-based microrobots,holding many new possibilities for precise immune regulation and treatment for immune-related diseases.
基金This work is supported by the National Natural Science Foundation of China （No. 21574094）, the Natural Science Foundation of Jiangsu Province （No. BK20150314） and Collaborative Innovation Center （CIC） of Suzhou Nano Science. It is also supported by the 111 Project and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions （PAPD）, the Fund for Excellent Creative Research Teams of Jiangsu Higher Education Institutions and the project-sponsored by SRF for ROCS, SEM,
文摘A micropump induces the flow of its surrounding fluids and is extremely promising in a variety of applications such as chemical sensing or mass transportation. However, it is still challenging to manipulate its pumping direction. In this stud~ we examine a binary micropump based on perovskite and poly[（2-methoxy-5-ethylhexyloxy）-1,4-phenylenevinylene] （MEHPPV）. The micropump is operational under the influence of light. Light exhibits significant versatility in controlling the pumping phenomenon of the micropump. It governs the start and stop and also regulates the velocity and directions. The direction control signifies immense opportunities for the development of micropumps with unprecedented pumping behaviors and functions （such as heartbeat-like pumping, rectification, and amplification）. This makes them potentially useful in various fields. Hence, it is expected that the micropump reported in the current study could act as a key step towards the further development of more sophisticated micropumps for diverse applications.
基金supported by the Natural Science Foundation of Guangdong Province, China (Grant Nos. 8251063101000007, 10151063101000009 and 9451063101002082)the Scientific & Technological Plan of Guangdong Province (Grant Nos. 2008B010200004, 2010B010600030 and 2009B011100003)+2 种基金the National Natural Science Foundation of China(Grant Nos. 61078046 and 10904042)the Key Project of Chinese Ministryof Education (Grant No. 210157)the Scientific & Technological Project of Education Department of Hubei Province (Grant No. D20101104)
文摘In order to promote the light output powers of GaN-based light emitting diodes (LEDs), two kinds of novel corrosive liquidshave been developed in this paper to roughen the surface of the indium tin oxide (ITO) current spreading layer of LEDs. As aresult, the textured transparent ITO layer greatly enhanced the external quantum efficiency of the LEDs. Provided that a wafersample was dipped in a kind of corrosive liquid developed by us for only about 60 s, the light output powers of the LEDs canbe promoted by 24.7%, compared with conventional GaN-based LEDs. It is obvious that the presented method is simple, rapidand cost-effective.
文摘Appropriate and adequate lighting at select locations on roadways is essential for roadway safety. As the lighting technologies advance, many Wpes of new lighting devices have been developed for roadway lightings. The most promising new lighting technologies for roadway lighting include light emitting diode, induction, plasma, and metal halide lighting systems. A study was conducted to compare the new systems with the conventional high pressure sodium systems that are currently used on the Indiana roadway systems. In this study, the engineering issues, were analyzed such as illuminance, color rendering, power usage, cost effectiveness, and approval procedures for new roadway lighting systems. This paper, however, presents only the study findings related to cost effectiveness of the evaluated roadway lighting systems. Illustrated in this paper are the main features of the roadway lighting systems under evaluations, installations of the new lighting systems, measurements of power consumptions, and life cycle cost analyses of the lighting systems. Through this study, experience and knowledge have been obtained on the installations, power measurements, and cost effectiveness of the new types of the roadway lighting devices. The actual power values of various luminaires were obtained by measuring the electric current with a multi-meter. It was found that the differences between the rated and measured power values could be significant. The results of the life cycle cost analysis indicate that the lower life cycle costs of some of the alternative lighting devices are attributed to their relatively lower electricity usages and longer lamp/emitter replacement cycles.
基金Project supported by the National High Technology Research and Development Program of China(No.SQ2008AA03Z402).
文摘This paper reports a new method of fabricating AlGaInP-based nanorod light emitting diodes（LEDs） by using self-assembly metal layer nanomasks and inductively coupled plasma.Light-power measurements indicate that the scattering of photons considerably enhances the probability of escaping from the nanorod LEDs.The light-intensity of the nanorod LED is increased by 34%for a thin GaP window layer,and by 17%for an 8μm GaP window layer.The light-power of the nanorod LED is increased by 25%and 13%,respectively.
基金Project supported by the National High Technology Program of China (No.Y48A040000)
文摘The effect of patterned sapphire substrate（PSS） on the top-surface（P-Ga N-surface） and the bottomsurface（sapphire-surface） of the light output power（LOP） of Ga N-based LEDs was investigated, in order to study the changes in reflection and transmission of the Ga N-sapphire interface. Experimental research and computer simulations were combined to reveal a great enhancement in LOP from either the top or bottom surface of Ga N-based LEDs, which are prepared on patterned sapphire substrates（PSS-LEDs）. Furthermore, the results were compared to those of the conventional LEDs prepared on the planar sapphire substrates（CSS-LEDs）. A detailed theoretical analysis was also presented to further support the explanation for the increase in both the effective reflection and transmission of PSS-Ga N interface layers and to explain the causes of increased LOP values. Moreover, the bottom-surface of the PSS-LED chip shows slightly increased light output performance when compared to that of the top-surface. Therefore, the light extraction efficiency（LEE） can be further enhanced by integrating the method of PSS and flip-chip structure design.
基金Project supported by the Key Project of the National Natural Science Foundation of China(No.50835005)the National High Technology Research and Development Program of China(No.2009AA03A1A3)
文摘In order to determine the environmental effects on the luminescence properties of a phosphor layer for high-power light emitting diodes, a high humidity and temperature test （85℃/85%RH） and a thermal aging test （85℃） were performed on silicone/YAG phosphor composites. The luminescence properties of silicone/phosphor composites are monitored by a fluorescence spectrometer. The results show that high temperature could result in an increase in conversion efficiency of composites during the early aging stage and red shift of YAG phosphor; and high humidity could result in a significant decrease in conversion efficiency of composites while having a small influence upon the optimal excitation wavelength of the YAG phosphor.
