In this paper,a white organic light-emitting device(WOLEDs) with multiple-emissive-layer structure has been fabricated.The device has a simple structure of indium tin oxide(ITO)/NPB(20 nm)//DPVBi(20 nm)/CDBP:x Ir(btp)...In this paper,a white organic light-emitting device(WOLEDs) with multiple-emissive-layer structure has been fabricated.The device has a simple structure of indium tin oxide(ITO)/NPB(20 nm)//DPVBi(20 nm)/CDBP:x Ir(btp)2acac(10 nm)/Alq3(25 nm)/BCP(5 nm)/Cs F(1 nm)/Al(150 nm)(x= 0.15,2.5 and 3.0 wt%),where NPB and BCP are used as the hole-injecting layer,electron transporting and hole blocking layer,respectively.White light emission was realized in an OLED with 2.5% Ir(btp)2acac doping concentration.The device exhibits peak efficiency of 1.93 cd/A at 9 V and maximum brightness of 7005 cd/m^2 at 14 V.The Commission International de I'Eclairage(CIE)(1931) coordinates of white emission are well within the white zone,which moves from(0.35,0.33) to(0.26,0.30) when the applied voltage is varied from 5 V to 14 V.展开更多
Three different types of TiO2 nano powders were synthesized by a solution combustion synthesis （SCS） method using three different fuels and for comparison, another type of Ti2 nano powder was synthesized by calcinat...Three different types of TiO2 nano powders were synthesized by a solution combustion synthesis （SCS） method using three different fuels and for comparison, another type of Ti2 nano powder was synthesized by calcination of titanyl hydroxide. These TiO2 nano powders were used to fabricate photoelectrodes for the dye-sensitized solar cell （DSSC） and their performance was compared to that of the DSSC fabricated with Degussa P25 TiO2. The results showed that the SCS TiO2 could work well as photoelectrode for DSSC. The SCS TiO2 contained impurities of C and/or S, thus exhibiting visible light absorption and reduced band gap. The open circuit voltage and the fill factor both varied little among the various TiO2 and thus both had little effect on the photoelectrical conversion efficiency （η）. However, the variation of r/was seen to be in quite a good agreement with that of the short circuit current （Isc）, suggesting that r/was dominated by Isc. lsc was found to be enhanced by light scattering effect due to the presence of large particles but reduced by high impurity content due to an increase in electron transfer resistance. In addition, the specific surface area of the powders was found to be an important factor affecting the Isc and thus the η.展开更多
The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and ...The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and the PVK emissive layer.It is believed that the PEO layer plays a key role in enhancing the device performance.In comparison to the device with Ca/Al as the cathode,the performance of the PLED with PEO/Ca/Al cathode,including the driving voltage,luminance efficiency is significantly improved.These improvements are attributed to the introduction of a thin layer of PEO that can lower the interfacial barrier and facilitate electron injection.展开更多
We investigated optically controllable gray-level diffraction from a body-centered tetragonal photonic crystal that was based on an azo-dye-doped holographic polymer dispersed liquid crystal. The sample is fabricated ...We investigated optically controllable gray-level diffraction from a body-centered tetragonal photonic crystal that was based on an azo-dye-doped holographic polymer dispersed liquid crystal. The sample is fabricated by use of two-beam interference with multi-exposure. Bichromatic pumping beams at various intensities were used to pump the sample to change the concentration of the cis isomer and, in turn, modulate the effective index of the photonic crystals as well as their diffraction intensity. Three pumping processes were utilized to produce gray-level switching of diffractive light. This study demonstrates the optimum gray-level to be 15-level of up-step and down-step. The simulation of the diffraction intensity under bichromatic pumping sources was also studied.展开更多
A simple, low cost method for mass production to enhance the light extraction efficiency of GaN-related LEDs was proposed. With appropriate process parameters, the nature lithography of nanosphere can be used to fabri...A simple, low cost method for mass production to enhance the light extraction efficiency of GaN-related LEDs was proposed. With appropriate process parameters, the nature lithography of nanosphere can be used to fabricate two-dimensional nanostructures, including the nanomesh ZnO layer, photonic crystal (PhC) patterned p-GaN, and patterned sapphire substrates. Based on preliminary results, the extraction efficiencies of LEDs with these nanostructures can thus be improved and the nature lithography is demonstrated to be a promising method to be widely exploited in the manufacture of all kinds of LED devices.展开更多
As immunotoxicity assessments of newly developed biomaterials are often restricted to use in assessment of local tissue response at the implantation site,they do not always show an immune response acceptable to qualif...As immunotoxicity assessments of newly developed biomaterials are often restricted to use in assessment of local tissue response at the implantation site,they do not always show an immune response acceptable to qualify them for clinical use.We tested a new method to assess systemic toxicity:counting the CD4^(+) and CD8^(+) cells in the spleen.Three different biomaterials were subcutaneously implanted in three groups of rats for the same time period.After 31 days,their spleens were harvested,and CD4^(+) and CD8^(+) cells were counted.The mean CD4^(+)/CD8^(+) cell counts were 24.563.6/19.864.0(porous collagen matrix group),25.567.1/21.663.8[synthetic collagen matrix(DuragenVR)group]and 28.164.1/19.663.7(porcine dermis group).Differences in cell counts were not significant.The immunotoxic response generated against porous collagen matrix was comparable to that produced by a similar biomaterial already used clinically.This is,to the best of our knowledge,the first study on cytotoxic lymphocytes in the spleen to quantify systemic immune response to a biomaterial;however,such studies have been conducted with bacterial and viral antigens,and with vaccines.We believe that the present study provides a viable method for larger studies to confirm our current findings.展开更多
文摘In this paper,a white organic light-emitting device(WOLEDs) with multiple-emissive-layer structure has been fabricated.The device has a simple structure of indium tin oxide(ITO)/NPB(20 nm)//DPVBi(20 nm)/CDBP:x Ir(btp)2acac(10 nm)/Alq3(25 nm)/BCP(5 nm)/Cs F(1 nm)/Al(150 nm)(x= 0.15,2.5 and 3.0 wt%),where NPB and BCP are used as the hole-injecting layer,electron transporting and hole blocking layer,respectively.White light emission was realized in an OLED with 2.5% Ir(btp)2acac doping concentration.The device exhibits peak efficiency of 1.93 cd/A at 9 V and maximum brightness of 7005 cd/m^2 at 14 V.The Commission International de I'Eclairage(CIE)(1931) coordinates of white emission are well within the white zone,which moves from(0.35,0.33) to(0.26,0.30) when the applied voltage is varied from 5 V to 14 V.
基金Support of this research by the National Science Council of Taiwan under Grant No. NSC 100-2221-E-006-214partial support under Contract No. 101-D0204-6 by the Bureau of Energy, Ministry of Economic Affairs of Taiwanthe LED Lighting Research Center, NCKU
文摘Three different types of TiO2 nano powders were synthesized by a solution combustion synthesis （SCS） method using three different fuels and for comparison, another type of Ti2 nano powder was synthesized by calcination of titanyl hydroxide. These TiO2 nano powders were used to fabricate photoelectrodes for the dye-sensitized solar cell （DSSC） and their performance was compared to that of the DSSC fabricated with Degussa P25 TiO2. The results showed that the SCS TiO2 could work well as photoelectrode for DSSC. The SCS TiO2 contained impurities of C and/or S, thus exhibiting visible light absorption and reduced band gap. The open circuit voltage and the fill factor both varied little among the various TiO2 and thus both had little effect on the photoelectrical conversion efficiency （η）. However, the variation of r/was seen to be in quite a good agreement with that of the short circuit current （Isc）, suggesting that r/was dominated by Isc. lsc was found to be enhanced by light scattering effect due to the presence of large particles but reduced by high impurity content due to an increase in electron transfer resistance. In addition, the specific surface area of the powders was found to be an important factor affecting the Isc and thus the η.
基金the Office of R&D,National Cheng Kung University,Taiwan
文摘The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and the PVK emissive layer.It is believed that the PEO layer plays a key role in enhancing the device performance.In comparison to the device with Ca/Al as the cathode,the performance of the PLED with PEO/Ca/Al cathode,including the driving voltage,luminance efficiency is significantly improved.These improvements are attributed to the introduction of a thin layer of PEO that can lower the interfacial barrier and facilitate electron injection.
文摘We investigated optically controllable gray-level diffraction from a body-centered tetragonal photonic crystal that was based on an azo-dye-doped holographic polymer dispersed liquid crystal. The sample is fabricated by use of two-beam interference with multi-exposure. Bichromatic pumping beams at various intensities were used to pump the sample to change the concentration of the cis isomer and, in turn, modulate the effective index of the photonic crystals as well as their diffraction intensity. Three pumping processes were utilized to produce gray-level switching of diffractive light. This study demonstrates the optimum gray-level to be 15-level of up-step and down-step. The simulation of the diffraction intensity under bichromatic pumping sources was also studied.
基金the "National" Science Council for finan-cially supporting this research under contract No. NSC 96-2221-E-006-079-MY3 and NSC 98-2218-E-006-005-MY2supported by TDPA program (Grant No. TDPA 97-EC-17-A-07-S1-105)
文摘A simple, low cost method for mass production to enhance the light extraction efficiency of GaN-related LEDs was proposed. With appropriate process parameters, the nature lithography of nanosphere can be used to fabricate two-dimensional nanostructures, including the nanomesh ZnO layer, photonic crystal (PhC) patterned p-GaN, and patterned sapphire substrates. Based on preliminary results, the extraction efficiencies of LEDs with these nanostructures can thus be improved and the nature lithography is demonstrated to be a promising method to be widely exploited in the manufacture of all kinds of LED devices.
文摘As immunotoxicity assessments of newly developed biomaterials are often restricted to use in assessment of local tissue response at the implantation site,they do not always show an immune response acceptable to qualify them for clinical use.We tested a new method to assess systemic toxicity:counting the CD4^(+) and CD8^(+) cells in the spleen.Three different biomaterials were subcutaneously implanted in three groups of rats for the same time period.After 31 days,their spleens were harvested,and CD4^(+) and CD8^(+) cells were counted.The mean CD4^(+)/CD8^(+) cell counts were 24.563.6/19.864.0(porous collagen matrix group),25.567.1/21.663.8[synthetic collagen matrix(DuragenVR)group]and 28.164.1/19.663.7(porcine dermis group).Differences in cell counts were not significant.The immunotoxic response generated against porous collagen matrix was comparable to that produced by a similar biomaterial already used clinically.This is,to the best of our knowledge,the first study on cytotoxic lymphocytes in the spleen to quantify systemic immune response to a biomaterial;however,such studies have been conducted with bacterial and viral antigens,and with vaccines.We believe that the present study provides a viable method for larger studies to confirm our current findings.
