A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,0...A very-high color rendering index white organic light-emitting diode(WOLED) based on a simple structure was successfully fabricated. The optimized device exhibits a maximum total efficiency of 13.1 and 5.4 lm/W at 1,000 cd/m2. A peak color rendering index of 90 and a relatively stable color during a wide range of luminance were obtained. In addition, it was demonstrated that the 4,40,400-tri(9-carbazoyl) triphenylamine host influenced strongly the performance of this WOLED.These results may be beneficial to the design of both material and device architecture for high-performance WOLED.展开更多
The AlGaN-based deep ultraviolet light-emitting diodes（LED） with double electron blocking layers（d-EBLs） on both sides of the active region are investigated theoretically. They possess many excellent performances ...The AlGaN-based deep ultraviolet light-emitting diodes（LED） with double electron blocking layers（d-EBLs） on both sides of the active region are investigated theoretically. They possess many excellent performances compared with the conventional structure with only a single electron blocking layer, such as a higher recombination rate, improved light output power and internal quantum efficiency（IQE）. The reasons can be concluded as follows. On the one hand, the weakened electrostatic field within the quantum wells（QWs） enhances the electron–hole spatial overlap in QWs, and therefore increases the probability of radioactive recombination. On the other hand, the added n-AlGaN layer can not only prevent holes from overflowing into the n-side region but also act as another electron source, providing more electrons.展开更多
SiO2Al2O3 double dielectric stack layer was deposited on the surface of the GaN-based light-emitting diode (LED). The double dielectric stack layer enhances both the electrical characteristics and the optical output p...SiO2Al2O3 double dielectric stack layer was deposited on the surface of the GaN-based light-emitting diode (LED). The double dielectric stack layer enhances both the electrical characteristics and the optical output power of the LED because the first Al2O3 layer plays a role of effectively passivating the p-GaN surface and the second lower index SiO2 layer increases the critical angle of the light emitted from the LED surface. In addition, the effect of the Fresnel reflection is also responsible for the enhancement in output power of the double dielectric passivated LED. The leakage current of the LED passivated with Al2O3 layer was -3.46 × 10-11 A at -5 V, at least two and three orders lower in magnitude compared to that passivated with SiO2 layer (-7.14 × 10-9 A) and that of non-passivated LED (-1.9 × 10-8 A), respectively, which indicates that the Al2O3 layer is very effective in passivating the exposed GaN surface after dry etch and hence reduces nonradiative recombination as well as reabsorption of the emitted light near the etched surface.展开更多
We fabricate a kind of novel efficient blue fluorescent organic light emitting device（OLED） based on p-n heterojunctions composed of hole transporting layer（HTL） N,N ＇-bis（naphthalen-1-yl）-N,N ＇-bis（phenyl）-...We fabricate a kind of novel efficient blue fluorescent organic light emitting device（OLED） based on p-n heterojunctions composed of hole transporting layer（HTL） N,N ＇-bis（naphthalen-1-yl）-N,N ＇-bis（phenyl）-benzidine（NPB） and electron transporting layer（ETL） 4,7-diphnenyl-1,10-phenanthroline（BPhen）,into which a new blue material,DNCA（a derivation of N 6,N 6,N 12,N 12-tetrap-tolylchrysene-6,12-diamine）,is partially doped simultaneously,and double emitting layers are configured.With a turn-on voltage of 2.6 V at 1 cd/m 2,this type of OLED presents a maximum luminance efficiency（η max） of 8.83 cd/A at 5.818 mA/cm 2 and a maximum luminance of over 40000 cd/m 2.Meanwhile,the Commission Internationale De L＇Eclairage（CIE） coordinates of this device change slightly from（0.13,0.27） to（0.13,0.23） as the driving voltage increases from 3 V to 11 V.This improvement in the electroluminescent characteristics is attributed mainly to the ideal p-n heterojunction which can confine and distribute excitons evenly on two sides of the heterojunction interface so as to improve the carrier combination rate and expand the light-emitting region.展开更多
激光成像可以检测出皮棉中的白色异性纤维,而深色和有色的异性纤维反光性能差,激光成像难以检测。该文提出了一种基于LED与线激光的双光源一次成像方法,可以检测出各种颜色的异性纤维。试验以白色、深色和浅色共20种典型异性纤维和皮棉...激光成像可以检测出皮棉中的白色异性纤维,而深色和有色的异性纤维反光性能差,激光成像难以检测。该文提出了一种基于LED与线激光的双光源一次成像方法,可以检测出各种颜色的异性纤维。试验以白色、深色和浅色共20种典型异性纤维和皮棉作为样本,在相机曝光时间与光圈不变的条件下,逐步改变LED亮度和线激光功率,发现在RGB颜色空间,利用R(红色)通道,白色异性纤维与棉花的可分度随着激光功率的增大而增大,达到峰值之后又逐步减小;在HIS颜色空间,利用S(饱和度)通道,有色异性纤维与棉花的可分度随着LED亮度的增大而增大,达到峰值之后又逐步减小。在此基础上,该文获取了310幅棉花与异性纤维的图像,作出了基于R与S通道的图像可分度、LED亮度与激光功率的对应变化曲线,然后将两种曲线进行融合,在曝光时间106μs、光圈2.8C条件下,发现线激光功率7.01 m W、LED亮度3 326 lx时,白色异性纤维和深色、有色异性纤维与棉花的可分度最大。采用上述双光源成像参数和该文的成像装置获取840幅图像,通过简单的二值化图像分割算法,白色异性纤维的正确识别为84.1%,深色和有色异性纤维正确识别为93.9%,优于单独激光成像或单独LED成像的识别率。展开更多
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 Special Strategic Emerging Industries of Guangdong Province,China(Grant No.2012A080304006)the Major Scientific and Technological Projects of Zhongshan City,Guangdong Province,China(Grant No.2014A2FC204)the Forefront of Technology Innovation and Key Technology Projects of Guangdong Province,China(Grant Nos.2014B010121001 and 2014B010119004)
文摘The AlGaN-based deep ultraviolet light-emitting diodes（LED） with double electron blocking layers（d-EBLs） on both sides of the active region are investigated theoretically. They possess many excellent performances compared with the conventional structure with only a single electron blocking layer, such as a higher recombination rate, improved light output power and internal quantum efficiency（IQE）. The reasons can be concluded as follows. On the one hand, the weakened electrostatic field within the quantum wells（QWs） enhances the electron–hole spatial overlap in QWs, and therefore increases the probability of radioactive recombination. On the other hand, the added n-AlGaN layer can not only prevent holes from overflowing into the n-side region but also act as another electron source, providing more electrons.
文摘SiO2Al2O3 double dielectric stack layer was deposited on the surface of the GaN-based light-emitting diode (LED). The double dielectric stack layer enhances both the electrical characteristics and the optical output power of the LED because the first Al2O3 layer plays a role of effectively passivating the p-GaN surface and the second lower index SiO2 layer increases the critical angle of the light emitted from the LED surface. In addition, the effect of the Fresnel reflection is also responsible for the enhancement in output power of the double dielectric passivated LED. The leakage current of the LED passivated with Al2O3 layer was -3.46 × 10-11 A at -5 V, at least two and three orders lower in magnitude compared to that passivated with SiO2 layer (-7.14 × 10-9 A) and that of non-passivated LED (-1.9 × 10-8 A), respectively, which indicates that the Al2O3 layer is very effective in passivating the exposed GaN surface after dry etch and hence reduces nonradiative recombination as well as reabsorption of the emitted light near the etched surface.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60906022 and 60876046)the Tianjin Natural Science Foundation,China (Grant No. 10JCYBJC01100)
文摘We fabricate a kind of novel efficient blue fluorescent organic light emitting device（OLED） based on p-n heterojunctions composed of hole transporting layer（HTL） N,N ＇-bis（naphthalen-1-yl）-N,N ＇-bis（phenyl）-benzidine（NPB） and electron transporting layer（ETL） 4,7-diphnenyl-1,10-phenanthroline（BPhen）,into which a new blue material,DNCA（a derivation of N 6,N 6,N 12,N 12-tetrap-tolylchrysene-6,12-diamine）,is partially doped simultaneously,and double emitting layers are configured.With a turn-on voltage of 2.6 V at 1 cd/m 2,this type of OLED presents a maximum luminance efficiency（η max） of 8.83 cd/A at 5.818 mA/cm 2 and a maximum luminance of over 40000 cd/m 2.Meanwhile,the Commission Internationale De L＇Eclairage（CIE） coordinates of this device change slightly from（0.13,0.27） to（0.13,0.23） as the driving voltage increases from 3 V to 11 V.This improvement in the electroluminescent characteristics is attributed mainly to the ideal p-n heterojunction which can confine and distribute excitons evenly on two sides of the heterojunction interface so as to improve the carrier combination rate and expand the light-emitting region.
文摘激光成像可以检测出皮棉中的白色异性纤维,而深色和有色的异性纤维反光性能差,激光成像难以检测。该文提出了一种基于LED与线激光的双光源一次成像方法,可以检测出各种颜色的异性纤维。试验以白色、深色和浅色共20种典型异性纤维和皮棉作为样本,在相机曝光时间与光圈不变的条件下,逐步改变LED亮度和线激光功率,发现在RGB颜色空间,利用R(红色)通道,白色异性纤维与棉花的可分度随着激光功率的增大而增大,达到峰值之后又逐步减小;在HIS颜色空间,利用S(饱和度)通道,有色异性纤维与棉花的可分度随着LED亮度的增大而增大,达到峰值之后又逐步减小。在此基础上,该文获取了310幅棉花与异性纤维的图像,作出了基于R与S通道的图像可分度、LED亮度与激光功率的对应变化曲线,然后将两种曲线进行融合,在曝光时间106μs、光圈2.8C条件下,发现线激光功率7.01 m W、LED亮度3 326 lx时,白色异性纤维和深色、有色异性纤维与棉花的可分度最大。采用上述双光源成像参数和该文的成像装置获取840幅图像,通过简单的二值化图像分割算法,白色异性纤维的正确识别为84.1%,深色和有色异性纤维正确识别为93.9%,优于单独激光成像或单独LED成像的识别率。
