源自纳米半导体的高效率硅基电致发光

Holmes' group of university of Minnesota in United States demonstrated highly efficient electroluminescene originated from silicon nanoparticles with external quantum efficiencies of up to 8.6% in 2011. We apply this fund to systematically research and develop silicon based highly efficient electroluminescene originated from nanoscale semiconductors by using Holmes et al's results for reference and combining the experiences of silicon based electroluminescene in our research group in the last 20 years. On the premise of ensuring high efficiencies, we plan to change the Holmes et al's ITO based devices to silicon based devices, which means to employ bulk silicon or thin microcrystalline silicon film as the anodes of devices. The bandgap of silicon is 1.12 eV. The wavelength of electroluminescene is below 1.1 if silicon nanoparticles are used. To extend the range of the wavelength of electroluminescene, especially the wavelength of 1.55 which is the lowest loss wavelength for optical communications, we plan to extend the electroluminescene from silicon nanoparticles to the electroluminescene from Ge and PbS nanoparticles. Ge and PbS are indirect and direct bandgap semiconductors, whose bulk materials bandgaps are 0.67eV and 0.41eV, respectively. The wavelength of electroluminescene can be increased up to 1.85 and 3.0 , which include 1.3 and 1.55 band. According to quantum confinement effect, the wavelengths of electroluminescene originated from these three kinds of nanoparticles can be continuously tuned from near ultraviolet to 3 micron infrared as the sizes of Si, Ge and PbS nanoparticles are changed.

国际上，源自纳米硅的电致发光外量子效率长期处于低迷状态。2011年美国明尼苏达大学的Holmes研究组实现了源自纳米硅的效率高达8.6 %的电致发光。本基金申请拟借鉴该项研究成果，结合我们研究组近二十年来研究硅基电致发光的经验，加以系统研究，发展出源自纳米硅的硅基高效率电致发光，即将他们的ITO基改为硅基。为了保证源自纳米硅的硅基电致发光具有高效率，选择参数优化的硅片或微晶硅薄膜为阳极，并对阴极和发光结构中其它各层作相应的调整。还拟将发光源自纳米硅颗粒的高效率电致发光推广到发光分别源自纳米硅，纳米锗和纳米PbS颗粒等三种情况的高效率电致发光。通过改变纳米锗和纳米PbS颗粒的尺寸，使电致发光波长达到1.3和1.55微米波段。

本项目研制出:.（1）具有倒置结构的高效率Si量子点发光二极管。硅量子点的平均直径为2.6 nm。以具有高电子迁移率的ZnO 纳米粒子作为电子传输材料，以具有高空穴迁移率的TAPC为空穴传输材料，以PEI 修饰的ITO作低功函数阴极，以MoO3/Al作高功函数阳极。该二极管的发光效率高达2.7%，是迄今为止，国际上发表的倒置结构量子点发光二极管中报导过的最高发光效率。相关论文发表在Journal of Materials Chemistry C 2016, 4, 273。由于所有三位审稿人对论文均有好评，该论文被选为该刊物的封面论文。.(2) 研制出创新的全透明CdSSe/ZnS量子点发光二极管。其主要创新点是二极管具有一个透明的与其它部分以层压方法相结合的石墨烯阴极。发光二极管具有如下结构：玻璃/ITO/ZnO 纳米粒子/CdSSe/ZnS 量子点/TAPC/MoO3//石墨烯/PDMS/PET。其中TAPC和PDMS是有机材料，PET是透明塑料，PDMS具有将//以上和//以下两部分层压在一起的作用。该二极管在6.7V偏压下的电流效率为0.32 cd/A。其电致发光峰位于622 nm, 在该波长下二极管的透光度高达79.4%。此外，本项目还进行了铜/石墨烯复合阳极有机电致发光，优化纳米厚度多晶p-Si阳极有机发光二极管的发光效率和一种提高石墨烯阴极有机发光二极管发光效率的纳米技术等研究工作。