Intermediate-Adduct-Assisted Growth of Stable CsPbI 2 Br Inorganic Perovskite Films for High-Efficiency Semitransparent Solar Cells.

Thanks to the tunable bandgap and excellent photoelectric characteristics, perovskites have been widely used in semitransparent solar cells (ST-SCs). Most works present unsatisfactory power conversion efficiencies (PCEs) through reducing the thickness of the perovskite films because there is a trade-off between PCE and average visible transmittance (AVT). As a consequence, most PCEs are less than 12% when the AVT is higher than 20% due to the limited voltage (Voc ) and short-circuit current (Jsc ). Herein, a strategy of intermediate adduct (IMAT) engineering is developed to improve the film quality of the inorganic perovskite CsPbI2 Br, which is a challenging issue to limit its performance of efficiency and stability. A normal n-i-p-structured PSC based on the optimal CsPbI2 Br film delivers a PCE of 16.02% with excellent stability. Furthermore, through optimizing the electrode type and interface, the ST-PSC shows a high Voc larger than 1.2 V and the PCE reaches 14.01% and 10.36% under an AVT of 31.7% and 40.9%, respectively. This is the first demonstration of a CsPbI2 Br ST-PSC, and it outperforms most of other types of perovskites.