Zhang Xiaoliang, Liu Jianhua, Johansson Erik M J
Department of Chemistry-Ångström Laboratory, Uppsala University, 75120 Uppsala, Sweden.
Nanoscale. 2015 Jan 28;7(4):1454-62. doi: 10.1039/c4nr04463k.
The utilization of electron-hole pairs (EHPs) generated from multiple excitons in quantum dots (QDs) is of great interest toward efficient photovoltaic devices and other optoelectronic devices; however, extraction of charge carriers remains difficult. Herein, we extract photocharges from Ag2S QDs and investigate the dependence of the electric field on the extraction of charges from multiple exciton generation (MEG). Low toxic Ag2S QDs are directly grown on TiO2 mesoporous substrates by employing the successive ionic layer adsorption and reaction (SILAR) method. The contact between QDs is important for the initial charge separation after MEG and for the carrier transport, and the space between neighbor QDs decreases with more SILAR cycles, resulting in better charge extraction. At the optimal electric field for extraction of photocharges, the results suggest that the threshold energy (hνth) for MEG is 2.41Eg. The results reveal that Ag2S QD is a promising material for efficient extraction of charges from MEG and that QDs prepared by SILAR have an advantageous electrical contact facilitating charge separation and extraction.
量子点（QD）中多个激子产生的电子 - 空穴对（EHP）的利用对于高效光伏器件和其他光电器件具有重要意义；然而，电荷载流子的提取仍然困难。在此，我们从Ag2S量子点中提取光电荷，并研究电场对多激子产生（MEG）电荷提取的依赖性。通过连续离子层吸附和反应（SILAR）方法，将低毒性的Ag2S量子点直接生长在TiO2介孔衬底上。量子点之间的接触对于MEG后的初始电荷分离和载流子传输很重要，相邻量子点之间的间距随着更多SILAR循环而减小，从而实现更好的电荷提取。在提取光电荷的最佳电场下，结果表明MEG的阈值能量（hνth）为2.41Eg。结果表明，Ag2S量子点是一种有望从MEG中高效提取电荷的材料，并且通过SILAR制备的量子点具有有利于电荷分离和提取的电接触。
