Comprehensive passivation strategy for achieving inverted perovskite solar cells with efficiency exceeding 23% by trap passivation and ion constraint

Both surface and bottom of perovskite film suffer from high density of trap-assisted recombination losses in perovskite solar cells; therefore, an effective method suitable for minimizing the trap density of perovskite solar cells (PSCs) both at perovskite/hole transport layer interfaces and perovskite/electron transport layer is urgently required. Herein, a comprehensive passivation strategy for achieving high-performance inverted PSCs was demonstrated. The study shows that the inverted PSCs possess dual increase of efficiency by passivation of the surface and bottom, as well as grain boundaries of perovskite active layer. The unencapsulated PSCs from comprehensive passivation strategy achieved the highest power conversion efficiency of 23.33% with remarkable long-term stability when exposed to illumination and humidity. In addition, this work provides an original method to analyze the distribution of the interfacial trap density and ions accumulation density by using the combination process of capacitance–voltage (C-V) and drive-level capacitance profiling (DLCP) measurements, providing the direct evidence for reducing of trap density and inhibiting of ion accumulation at two interfaces of PSCs.