Perovskite solar cells integrated with blue cut-off filters for mitigating light-induced degradation

The stability of methylammonium (MA)-based perovskite solar cells (PSCs) remains one of the most urgent issues that need to be addressed. Inherent weak binding forces between MAs and halides cause the perovskite structure to become unstable under exposure to various external environmental factors such as moisture, oxygen, ultraviolet radiation, and heat. In particular, the degradation of perovskite films under light exposure accelerates the deterioration of the device, mainly due to the migration of halide ions. In this study, we investigated the effect of light energy on the degradation of inverted PSCs by introducing red ( = 610-800 nm), green (500-590 nm), and blue (300-500 nm) light-pass filters. After 30 h, the inverted PSCs of blue-light-induced devices retained a power conversion efficiency (PCE) of 70%, while those of the green and red light-induced devices retained PCEs of 85% and 90%, respectively. Direct evidence of light-induced degradation was obtained by investigating morphological changes in the perovskite films and the amount of ion accumulation on the Ag electrode. This evidence highlights the varying effect of light with different energies on device degradation. Furthermore, to minimize light-induced device degradation, we designed two types of blue cut-off filters that can selectively block light ranging from  = 400 to 500 nm, comprising a multilayered inorganic metasurface. An optical simulation was used to optimize the performance of the designed filters. By investigating the changes in the photovoltaic parameters and the amount of ion accumulation on the Ag electrode, we confirmed that integrating blue cut-off filters into PSCs greatly improved the operational lifetime of the devices.