Dual-Functional Additive to Simultaneously Modify the Interface and Grain Boundary for Highly Efficient and...

The efficiency loss and stability issues of perovskite devices mainly derive from nonradiative recombination, caused by detrimental defects in the perovskite bulk and at the interface between the perovskite absorber and charge transport layer. Therefore, the passivation of these defects is of great concern in achieving high-performance perovskite devices. Here, we report the incorporation of potassium phenyl trifluoroborate (KC₆H₅BF₃) into perovskite films to realize simultaneous passivation of the grain boundaries and the perovskite/SnO₂ interface. Apart from the bulk passivation of K⁺, the accumulation of C₆H₅BF₃^- at the buried interface contributes to the compact contact between the perovskite absorber and SnO₂ layer and also the perfect columnar perovskite grains. As a result, the KC₆H₅BF₃-containing perovskite films exhibit low trap density. The distinct enhancements of open-circuit voltage and photoelectric conversion efficiency are obtained together with negligible hysteresis. The open-circuit voltage of the KC₆H₅BF₃-containing device increases from 1.09 to 1.18 V, and the corresponding efficiency increases from 19.69 to 22.33%. The finding in this work shows the superiority of the dual-functional additive for preparing highly efficient perovskite devices.