Employing ZnS as a capping material for PbS quantum dots and bulk heterojunction solar cells

采用ZnS作为PbS量子点包覆材料及其体相太阳电池研究（英文）

Formation of bulk heterojunctions by incorporating colloidal quantum dots into a mesoporous substrate is anticipated to yield efficient charge collection and complete light absorption. However, it is still challenging in view of the bulky nature of the colloidal quantum dots and the ex situ deposition route. In this study, the feasibility of employing ZnS as a capping material for PbS quantum dots is dissected by carefully designed control experiments, with reference to the formation of bulk heterojunctions by successive ionic layer adsorption and reaction(SILAR) at ambient conditions.The results reveal that the underlying ZnS layer facilitates the PbS deposition by an ion exchange process, while the overlaying ZnS layer tends to cover the PbS in a manner similar to a physical stacking process. Therefore, PbS quantum dots capped with amorphous ZnS are developed with the SILAR technique, which could be used to fill up the mesoporous substrates and thus construct bulk heterojunctions.The hole collection is the limiting factor of such bulk heterojunction solar cells, as demonstrated by inserting a conductive polymer layer in the control devices. Further development of the quantum dot system is discussed in consideration of the fundamental issues presented in this study.

将胶体量子点引入到介孔基体中形成体相异质结预期能够产生高效的电荷收集和完全的光吸收.然而,鉴于胶体量子点个体体积较大和薄膜异位生长的特性,形成这样的异质结结构仍然存在巨大挑战.本论文针对此问题,通过严谨的实验设计,分析了采用连续离子层吸附反应法(SILAR)以ZnS作为PbS量子点包覆材料的可行性.实验结果表明底层ZnS通过离子交换的方式促进PbS的沉积,而顶层ZnS趋于通过物理堆垛的方式覆盖PbS,进而形成非晶态ZnS包覆的PbS量子点结构.该方法可用以填充介孔基体而形成体相异质结结构.在该体相异质结器件中加入导电有机物的研究表明该体系太阳电池受限于空穴收集.在此基础上,讨论了该体系量子点太阳电池进一步提升的途径.