随着科学技术的发展,我国的 LED 半导体照明技术有了很大进展,相关部门不断出台政策来支持其发展。LED 是 一种重要的新型固态光源,具有环保、节能、高效、长寿等优点。但现阶段在 LED 半导体照明的测试方面仍然存在一些问题, 本文首先...随着科学技术的发展,我国的 LED 半导体照明技术有了很大进展,相关部门不断出台政策来支持其发展。LED 是 一种重要的新型固态光源,具有环保、节能、高效、长寿等优点。但现阶段在 LED 半导体照明的测试方面仍然存在一些问题, 本文首先分析了测试中存在的问题,并有针对性的提出了改进的措施,以更好的促进我国 LED 半导体照明行业的健康发展。展开更多
Exciton(or spin)statistics is a physical principle based on the statistics of spin multiplicity.In electroluminescence,injected electrons and holes have randomized spin states,and usually form singlet or triplet excit...Exciton(or spin)statistics is a physical principle based on the statistics of spin multiplicity.In electroluminescence,injected electrons and holes have randomized spin states,and usually form singlet or triplet excitons in the ratio of 1:3.Exciton statistics determines that the upper limit of internal quantum efficiency is 25%in fluorescent devices,since only singlet exciton can decay radiatively.However,both experimental and theoretical evidence indicate that the actual efficiency can exceed the exciton statistics limit of 25%by utilizing materials with special electronic structure and optimized device structures.These results bring light to break through the exciton statistics limit and develop new-generation fluorescent materials with low cost and high efficiency.Recently,the exciton statistics,which has attracted great attention in the past decade,is being rejuvenated due to the discovery of some fluorescent materials with abnormally high efficiencies.In view of their significance in theoretical research of organic semiconductors and developing new-generation OLED materials,such materials are widely investigated in both academic institutions and industry.Several key issues still require further clarification for this kind of materials,such as the molecular design concepts.Herein,we review the progress of the materials with efficiency exceeding the exciton statistics limit,and the routes to improve exciton utilization efficiency.In the end,we present an innovative pathway to fully harvest the excitons in fluorescent devices,namely,"hot exciton"model and relevant fluorescence material with hybridized local and charge-transfer(HLCT)excited state.展开更多
文摘随着科学技术的发展,我国的 LED 半导体照明技术有了很大进展,相关部门不断出台政策来支持其发展。LED 是 一种重要的新型固态光源,具有环保、节能、高效、长寿等优点。但现阶段在 LED 半导体照明的测试方面仍然存在一些问题, 本文首先分析了测试中存在的问题,并有针对性的提出了改进的措施,以更好的促进我国 LED 半导体照明行业的健康发展。
基金financially supported by the National Science Foundation of China(51073069,51273078)the National Basic Research Program of China(2013CB834801)
文摘Exciton(or spin)statistics is a physical principle based on the statistics of spin multiplicity.In electroluminescence,injected electrons and holes have randomized spin states,and usually form singlet or triplet excitons in the ratio of 1:3.Exciton statistics determines that the upper limit of internal quantum efficiency is 25%in fluorescent devices,since only singlet exciton can decay radiatively.However,both experimental and theoretical evidence indicate that the actual efficiency can exceed the exciton statistics limit of 25%by utilizing materials with special electronic structure and optimized device structures.These results bring light to break through the exciton statistics limit and develop new-generation fluorescent materials with low cost and high efficiency.Recently,the exciton statistics,which has attracted great attention in the past decade,is being rejuvenated due to the discovery of some fluorescent materials with abnormally high efficiencies.In view of their significance in theoretical research of organic semiconductors and developing new-generation OLED materials,such materials are widely investigated in both academic institutions and industry.Several key issues still require further clarification for this kind of materials,such as the molecular design concepts.Herein,we review the progress of the materials with efficiency exceeding the exciton statistics limit,and the routes to improve exciton utilization efficiency.In the end,we present an innovative pathway to fully harvest the excitons in fluorescent devices,namely,"hot exciton"model and relevant fluorescence material with hybridized local and charge-transfer(HLCT)excited state.
