Boost the efficiency of nickel oxide-based formamidinium-cesium perovskite solar cells to 21% by using coumarin 343 dye as defect passivator

Inverted perovskite solar cells (PSCs) based on formamidinium-cesium (FACs) perovskites with nickel oxide as hole transport layer (HTL) have attracted much attention due to their good stability. However, their open-circuit voltage (V-OC) and efficiencies lag far behind those of inverted PSCs based on organic HTLs. Here, we introduce an organic dye coumarin 343 (C343) as a molecular additive into the perovskite to reduce V-OC loss and improve the efficiency of nickel oxide-based inverted PSCs. We demonstrate that the strong coordination between the carboxyl groups in C343 and under-coordinated Pb2+ not only optimizes perovskite crystal growth during perovskite formation, but also reduces the defects densities within perovskite films. As a result, our C343 doped PSCs achieve an optimal efficiency of 20.9% (certified 20.2%), which is one of the highest efficiencies for FACs perovskite and nickel oxide based inverted PSCs reported so far. Moreover, the utilization of C343 also benefits devices' stability, making the devices maintain over 94% and 95% of the initial PCE after aging at 85 degrees C for 500 h in N-2 glovebox and operation under continuous 1 sun illumination with the maximum power point (MPP) tracking at the temperature around 65 degrees C in ambient air for 500 h, respectively.

Automated summary

This study introduces an organic dye C343 into the perovskite to improve the efficiency and stability of nickel oxide-based inverted perovskite solar cells. The strong coordination between C343 and Pb2+ optimizes perovskite crystal growth and reduces defects densities within perovskite films, leading to one of the highest efficiencies reported for FACs perovskite and nickel oxide based inverted PSCs. Additionally, the utilization of C343 benefits devices' stability, maintaining performance over 94% and 95% after aging and continuous operation for 500 hours, respectively.