Rubidium fluoride additive for high-efficiency and low-hysteresis all-inorganic CsPbI3 perovskite solar cells

All-inorganic CsPbI3 perovskite solar cells (PSCs) technology is gradually maturing because of its excellent photoelectric characteristics. However, the hysteresis phenomenon induced by ion migration in the perovskite film not only seriously affects the performance of the device, but also accelerates the degradation of the film, which limits the further improvement of power conversion efficiency (PCE) for CsPbI3 PSCs. Herein, in this paper, a new inorganic fluorine-containing additive rubidium fluoride (RbF) was introduced as a precursor additive. The incorporation of RbF effectively improved the crystallization kinetics of CsPbI3 perovskite film and effectively suppressed the occurrence of hysteresis. The defects on the CsPbI3 perovskite film are remarkably inhibited and the carrier dynamics process is greatly promoted with the incorporation of 0.03 mol% RbF. In addition, the non-radiative recombination is significantly suppressed, and the device stability is substantially improved. In particular, by doping 0.03 mol% RbF into the CsPbI3, the hysteresis index of PSCs decreases to 0.003. The introduction of RbF effectively improves the device performance, and the highest efficiency has reached to 17.21%. The environmental stability has also been significantly enhanced with the RbF doping.