Enhancement of light extraction in a GaInN light-emitting diode （LED） employing an omni-directional reflector （ODR） consisting of GaN, SnO2 nanorod and an Ag layer was presented. The ODR comprises a transparent, q...Enhancement of light extraction in a GaInN light-emitting diode （LED） employing an omni-directional reflector （ODR） consisting of GaN, SnO2 nanorod and an Ag layer was presented. The ODR comprises a transparent, quarterwave layer of SnO2 nanorod claded by silver and serves as an ohmic contact to p-type GaN. Transparent SnO2 sols were obtained by sol-gel method from SnCl2·2H2O, and SnO2 thin films were prepared by dip-coating technique. The average size of the spherical SnO2 particles obtained is 200 nm. The refractive index of the nanorod SnO2 film layer is 2.01. The GaInN LEDs with GaN/SnO2/Ag ODR show a lower forward voltage. This was attributed to the enhanced reflectivity of the ODR that employs the nanorod SnO2 film layer. Experimental results show that ODR-LEDs have lower optical losses and higher extraction efficiency as compared to conventional LEDs with Ni/Au contacts and conventional LEDs employing a distributed Bragg reflector （DBR）.展开更多
We demonstrate a soft lithography approach for fabrication of a topographically patterned polyvinyl alcohol （PVA） liquid-crystal （LC） alignment layer. This specific approach employs modified micromolding in capill...We demonstrate a soft lithography approach for fabrication of a topographically patterned polyvinyl alcohol （PVA） liquid-crystal （LC） alignment layer. This specific approach employs modified micromolding in capillaries for negative replication of the PVA microstructures on indium tin oxide （ITO） substrates from patterned poly （dimethylsiloxane） molds in a single step, leading to planar alignment on the desired regions. By doping with polyhedral oligomeric silsesquioxane nanoparticles, which can induce vertical alignment on bare ITO surfaces, periodic LC phase gratings based on an alternating vertical-aligned/hybrid-aligned nematic geometry are presented as an application, and a theoretical model was used to simulate and examine the experimental results.展开更多
In this letter, we propose a voltage-controlled optical filter based on electrowetting. The device is made of a transparent cubic cell filled with two immiscible liquids having three indium tin oxide electrodes fabric...In this letter, we propose a voltage-controlled optical filter based on electrowetting. The device is made of a transparent cubic cell filled with two immiscible liquids having three indium tin oxide electrodes fabricated on the bottom substrate of the cell. A conductive droplet carrying a color filter is placed on the ITO electrode and the surrounding liquid is density-matched silicone oil. Under zero bias, the droplet is placed in the middle of tile substrate and white light passes through the filter and we can see red light on the screen. When a voltage is applied to the device, the filter moves with the liquid based on electrowetting effect, we can see the white light on the screen. Due to the movement of the liqnid, our device functions as an optical switcher. The switch trine of the device is -70 ms. The proposed device has a wide application in optical communication. electronic display, and optical switch.展开更多
The conversion of CO_2 to liquid hydrocarbon fuels using solar energy is gaining attraction as a means to deal with climate change and energy depletion,and assessment for related thermochemical cycles has attracted gr...The conversion of CO_2 to liquid hydrocarbon fuels using solar energy is gaining attraction as a means to deal with climate change and energy depletion,and assessment for related thermochemical cycles has attracted great interests in recent years.Here,we perform the thermodynamical analysis on solar-aided CO_2 conversion reactions based on Tin oxides.The equilibrium compositions,production purity and CO_2 conversion are obtained.Also,the variations of conversion efficiency with respect to temperature,normal beam solar insolation,mean flux concentration ratio,initial CO_2 to SnO ratio and heat recuperation percentage are revealed.Our results indicate the initial CO_2 to SnO ratio,χ_(ini),has an evident impact on conversion efficiency andχ_(ini)=0.5,T=700 K andχ_(ini)=1,T=950 K,are favourable for solid C and gaseous CO production,respectively.The calculated maximum cycle efficiency with direct work production is 0.340 at T=950 K andχ_(ini)=1,demonstrating the high conversion efficiency of the proposed system.展开更多
Density functional theory calculations were used to unravel the mechanism of CO_2 electroreduction on SnO_x surfaces. Under highly reducing conditions(<-0.6 V vs. RHE), the SnO(101) surface with oxygen vacancies is...Density functional theory calculations were used to unravel the mechanism of CO_2 electroreduction on SnO_x surfaces. Under highly reducing conditions(<-0.6 V vs. RHE), the SnO(101) surface with oxygen vacancies is likely the active phase for CO_2 reduction. We showed that the proton-electron transfer to adsorbed *CO_2 forming *OCHO, a key intermediate for producing HCOOH, is energetically more favorable than the formation of *COOH, justifying the selectivity trends observed on Sn-based electrocatalysts. With linear scaling relations, we propose the free formation energy of *CO_2 at the oxygen vacancy as the reactivity descriptor. By engineering the strain of the SnO(101) surface, the selectivity towards HCOOH can be further optimized at reduced overpotentials.展开更多
基金the Opening Foundation of China JiLiang University under Grant No.2006KF07
文摘Enhancement of light extraction in a GaInN light-emitting diode （LED） employing an omni-directional reflector （ODR） consisting of GaN, SnO2 nanorod and an Ag layer was presented. The ODR comprises a transparent, quarterwave layer of SnO2 nanorod claded by silver and serves as an ohmic contact to p-type GaN. Transparent SnO2 sols were obtained by sol-gel method from SnCl2·2H2O, and SnO2 thin films were prepared by dip-coating technique. The average size of the spherical SnO2 particles obtained is 200 nm. The refractive index of the nanorod SnO2 film layer is 2.01. The GaInN LEDs with GaN/SnO2/Ag ODR show a lower forward voltage. This was attributed to the enhanced reflectivity of the ODR that employs the nanorod SnO2 film layer. Experimental results show that ODR-LEDs have lower optical losses and higher extraction efficiency as compared to conventional LEDs with Ni/Au contacts and conventional LEDs employing a distributed Bragg reflector （DBR）.
基金supported by the Fundamental Research Funds for the Central Universities (No. 20720140518)the National Natural Science Foundation of China (No. 61308048)the Natural Science Foundation of Fujian Province (No. 2013J01244)
文摘We demonstrate a soft lithography approach for fabrication of a topographically patterned polyvinyl alcohol （PVA） liquid-crystal （LC） alignment layer. This specific approach employs modified micromolding in capillaries for negative replication of the PVA microstructures on indium tin oxide （ITO） substrates from patterned poly （dimethylsiloxane） molds in a single step, leading to planar alignment on the desired regions. By doping with polyhedral oligomeric silsesquioxane nanoparticles, which can induce vertical alignment on bare ITO surfaces, periodic LC phase gratings based on an alternating vertical-aligned/hybrid-aligned nematic geometry are presented as an application, and a theoretical model was used to simulate and examine the experimental results.
基金supported by the National Natural Science Foundation of China(Nos.61225022 and 61320106015)the National "973" Program of China(No.2013CB328802)+1 种基金the National "863" Program of China(No.2012AA011901)the Research Program of Sichuan Province,China(No.2013TD0002)
文摘In this letter, we propose a voltage-controlled optical filter based on electrowetting. The device is made of a transparent cubic cell filled with two immiscible liquids having three indium tin oxide electrodes fabricated on the bottom substrate of the cell. A conductive droplet carrying a color filter is placed on the ITO electrode and the surrounding liquid is density-matched silicone oil. Under zero bias, the droplet is placed in the middle of tile substrate and white light passes through the filter and we can see red light on the screen. When a voltage is applied to the device, the filter moves with the liquid based on electrowetting effect, we can see the white light on the screen. Due to the movement of the liqnid, our device functions as an optical switcher. The switch trine of the device is -70 ms. The proposed device has a wide application in optical communication. electronic display, and optical switch.
基金supported by the National Natural Science Foundation of China (Grant No. 51476163)the Institute of Electrical Engineering, Chinese Academy of Sciences (Grant No. Y770111CSC)
文摘The conversion of CO_2 to liquid hydrocarbon fuels using solar energy is gaining attraction as a means to deal with climate change and energy depletion,and assessment for related thermochemical cycles has attracted great interests in recent years.Here,we perform the thermodynamical analysis on solar-aided CO_2 conversion reactions based on Tin oxides.The equilibrium compositions,production purity and CO_2 conversion are obtained.Also,the variations of conversion efficiency with respect to temperature,normal beam solar insolation,mean flux concentration ratio,initial CO_2 to SnO ratio and heat recuperation percentage are revealed.Our results indicate the initial CO_2 to SnO ratio,χ_(ini),has an evident impact on conversion efficiency andχ_(ini)=0.5,T=700 K andχ_(ini)=1,T=950 K,are favourable for solid C and gaseous CO production,respectively.The calculated maximum cycle efficiency with direct work production is 0.340 at T=950 K andχ_(ini)=1,demonstrating the high conversion efficiency of the proposed system.
基金financial support from the American Chemical Society Petroleum Research Fund (ACS PRF 55581-DNI5)the Institute for Critical Technology and Applied Science (ICTAS-J0663175)the NSF CBET Catalysis and Biocatalysis Program (CBET-1604984)
文摘Density functional theory calculations were used to unravel the mechanism of CO_2 electroreduction on SnO_x surfaces. Under highly reducing conditions(<-0.6 V vs. RHE), the SnO(101) surface with oxygen vacancies is likely the active phase for CO_2 reduction. We showed that the proton-electron transfer to adsorbed *CO_2 forming *OCHO, a key intermediate for producing HCOOH, is energetically more favorable than the formation of *COOH, justifying the selectivity trends observed on Sn-based electrocatalysts. With linear scaling relations, we propose the free formation energy of *CO_2 at the oxygen vacancy as the reactivity descriptor. By engineering the strain of the SnO(101) surface, the selectivity towards HCOOH can be further optimized at reduced overpotentials.
