Performance improvement of inverted two-dimensional perovskite solar cells using a non-fullerene acceptor as the trap passivator†

Recently, Ruddlesden-Popper two-dimensional (2D) perovskite solar cells (PSCs) have been intensively studied, owing to their high power-conversion-efficiency (PCE) and excellent long-term stability. In this work, we improved the performance of 2D PSCs by adding a non-fullerene acceptor (indacenodithiophene, IDIC) to the perovskite layer. We found that IDIC efficiently passivates the charge traps in the perovskite film and enhances the electron transport properties of PSCs. After adding 1.5 mg mL(-1) IDIC to the perovskite layer, the average PCE of the 2D PSCs significantly improved, from 10.19% to 12.78%, corresponding to the 25% enhancement. The PCE improvement was mainly caused by the simultaneous enhancement of the short-circuit current density and fill factor. Moreover, the long-term stability of the studied 2D PSCs also improved, with the PCE degradation after 10 days significantly reduced, from 14.9% to 9.5%, which can be attributed to the enhanced moisture resistance of the perovskite layer. The best 2D PSC with added IDIC exhibited a PCE of 13.23%, with a stable power output and negligible hysteresis. Our results demonstrate that the addition of IDIC to 2D perovskite is a simple and effective method for fabricating high-performance 2D PSCs.