A Facile Solvent Strategy Enables Morphology Controllable Perovskite Films for CsPbBr3 Perovskite Solar Cells

The CsPbBr 3 perovskite solar cells (PSCs) display extensive potential due to their good thermal and humidity stability, but the presence of heterogeneous phases severely limits the further improvement of device performance. Phase‐pure monoclinic CsPbBr 3 can be stabilized by using the printable mesoscopic device structure. However, it is challenging to obtain high‐quality perovskite crystals in such confined space. Herein, a solvent strategy is used for improving the perovskite crystallization in the printable mesoscopic structure. By using N‐methylformamide as the precursor solvent, the PbBr 2 exhibits a more uniform and controllable distribution, which benefits the CsPbBr 3 crystallization. As a result, the CsPbBr 3 inside the pores showed obvious orientation at (100) lattice plane and (110) crystal plane. The efficiency of modified PSCs increases from 7.53% to 8.32%. Based on the device with effective area of 1 cm 2 , the PSCs obtain a power conversion efficiency of 5.62%. In addition, PSCs show no obvious attenuation after 1000 h of maximum power point tracking, displaying the excellent illumination stability.