Exploring the Effect of Double Additives in Mixed 2D/3D Sn-Based Perovskite Solar Cells

Abstract

Additive doping improves the tin (Sn)-based perovskite film morphology and ambient stability, however the function of additive in the perovskite film is limited, especially when two or more additives are used. In this study, the effect of double additives such as 2-phenylethylammonium iodide (PEAI) and ethylenediammonium diiodide (EDAI2) on the formamidinium tin iodide (FASnI3) films were explored. The perovskite film with only PEAI has showed several pinholes which is not suitable for ideal large area solar cell. While mixing of the two additives for an optimum concentration of PEAI (8 mol%) and EDAI2 (1 mol%) produced pinhole-free compact perovskite film with superior crystallinity, preferential orientation, low background charge carrier density, reduced trap states, and suppressed non-geminated recombination losses. The reduced dimensionality and favored perovskite layer stacking led to better interlayer coupling and increase charge transfer at interfaces. Consequently, a high-power conversion efficiency (PCE) of 8.47% and an open circuit voltage (V OC) of 0.634 V were achieved for the perovskite solar cell (PSC) with mixed additive, and the fabricated solar cells exhibits excellent stability for 5 days in ambient conditions.