Optimizing the Performance of CsPbI(3)-Based Perovskite Solar Cells via Doping a ZnO Electron Transport Layer Coupled with Interface Engineering

Interface engineering has been regarded as an effective and noninvasive means to optimize the performance of perovskite solar cells (PSCs). Here, doping engineering of a ZnO electron transport layer (ETL) and CsPbI(3)/ZnO interface engineering via introduction of an interfacial layer are employed to improve the performances of CsPbI(3)-based PSCs. The results show that when introducing a TiO(2) buffer layer while increasing the ZnO layer doping concentration, the open-circuit voltage, power conversion efficiency, and fill factor of the CsPbI(3)-based PSCs can be improved to 1.31 V, 21.06%, and 74.07%, respectively, which are superior to those of PSCs only modified by the TiO(2) buffer layer or high-concentration doping of ZnO layer. On the one hand, the buffer layer relieves the band bending and structural disorder of CsPbI(3). On the other hand, the increased doping concentration of the ZnO layer improves the conductivity of the TiO(2)/ZnO bilayer ETL because of the strong interaction between the TiO(2) and ZnO layers. However, such phenomena are not observed for those of a PCBM/ZnO bilayer ETL because of the weak interlayer interaction of the PCBM/ZnO interface. These results provide a comprehensive understanding of the CsPbI(3)/ZnO interface and suggest a guideline to design high-performance PSCs. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-019-0320-y) contains supplementary material, which is available to authorized users.