Enhanced Efficiency and Stability of NiOx-Based Perovskite Solar Cells Using [6,6]-Phenyl-C₆₁-butyric Acid Methyl-Doped Poly(9-vinylcarbazole)-Modified Layer

In recent years, the power conversion efficiency (PCE) of NiOx-based perovskite solar cells (PSCs) has increased by leaps and bounds, reaching more than 20%. However, the structure of PSCs is unstable under high humidity, high temperature, and UV irradiation environment, which is easily decomposed. To improve the limitations of the typical structure of the perovskite layer, the strategy of p-type poly(9-vinylcarbazole) (PVK) doped with a small amount of [6,6]-phenyl-C61-butyric acid methyl (PCBM) has been developed to modify the interface between the perovskite layer and the electron transport layer (ETL). A dense quasi-two-dimensional structure layer is formed onto the three-dimensional perovskite layer, and better crystallinity of perovskite with less defects and superior contact properties at the perovskite/PCBM interface can be obtained under PCBM-doped PVK modification, which improve perovskite stability, boost carrier transport and extraction, and reduce carrier recombination. Furthermore, the PCBM-doped PVK-modified layer further boosts electron tunneling from the perovskite layer to PCBM ETL assisted with PCBM dopants. Therefore, PCEs of Sr@NiOx-based PSCs with PCBM-doped PVK modification were increased to 20.91 from 16.54% of the reference PSCs. Furthermore, PSCs with PCBM-doped PVK modification show better anti-UV, moisture, and thermal resistance.