调控钙钛矿异质结太阳能电池电场性质以提高工作稳定性

Eliminating the electric field response in a perovskite heterojunction solar cell to improve operational stability

钙钛矿太阳能电池因其优异的光电转换性能受到了广泛关注.目前该电池的光电转换效率已经超过25%.然而,电池在工作状态下表现出了较为严重的性能衰减问题,在一定程度上限制了其快速商业化过程.研究表明,电场驱使下的离子迁移是影响电池稳定性的一个本征因素.本文从异质结设计的角度,提出在n型电子传输层和钙钛矿光吸收层间引入高掺杂p型半导体层,构建n-p^(+)-钙钛矿-空穴传输层结构的异质结电池.该异质结电池的内建电场被限制在电子传输层和p^(+)层内,而钙钛矿吸收层和空穴传输层保持中性状态.钙钛矿层内几乎不存在电场,外部偏置电压也不会施加在钙钛矿层上,由此消除了钙钛矿离子迁移的电场驱动力.更重要的是,该异质结电池可以保持高的光电转换效率,且p^(+)层材料具有较大的选择空间,对缺陷密度和迁移率等性质具有较大的容忍性.本文从材料和异质结结构设计角度为钙钛矿电池的稳定性提升提供了一条可行的路线.

Intrinsic and extrinsic ion migration is a very large threat to the operational stability of perovskite solar cells and is difficult to completely eliminate due to the low activation energy of ion migration and the existence of internal electric field.We propose a heterojunction route to help suppress ion migration,thus improving the operational stability of the cell from the perspective of eliminating the electric field response in the perovskite absorber.A heavily doped p-type(p^(+))thin layer semiconductor is introduced between the electron transporting layer(ETL)and perovskite absorber.The heterojunction charge depletion and electric field are limited to the ETL and p^(+)layers,while the perovskite absorber and hole transporting layer remain neutral.The p^(+)layer has a variety of candidate materials and is tolerant of defect density and carrier mobility,which makes this heterojunction route highly feasible and promising for use in practical applications.