Homojunction Perovskite Quantum Dot Solar Cells with over 1 µm‐Thick Photoactive Layer

Abstract The solution‐processed solar cells based on colloidal quantum dots (QDs) reported so far generally suffer from poor thickness tolerance and it is difficult for them to be compatible with large‐scale solution printing technology. However, the recently emerged perovskite QDs, with unique high defect tolerance, are particularly well‐suited for efficient photovoltaics. Herein, efficient CsPbI 3 perovskite QD solar cells are demonstrated first with over 1 µm‐thick active layer by developing an internal P/N homojunction. Specifically, an organic dopant 2,2′‐(perfluoronaphthalene‐2,6‐diylidene) dimalononitrile (F6TCNNQ) is introduced into CsPbI 3 QD arrays to prepare different carrier‐type QD arrays. The detailed characterizations reveal successful charge‐transfer doping of QDs and carrier‐type transformation from n‐type to p‐type. Subsequently, the P/N homojunction perovskite QD solar cell is assembled using different carrier‐type QDs, delivering an enhanced power conversion efficiency of 15.29%. Most importantly, this P/N homojunction strategy realizes remarkable thickness tolerance of QD solar cells, showing a record high efficiency of 12.28% for a 1.2 µm‐thick QD active‐layer and demonstrating great potential for the future printing manufacturing of QDs solar cells.