Large area,waterproof, air stable and cost effective efficient perovskite solar cells through modified carbon hole extraction layer

The conventional unstable and expensive hole transporting materials (HTM) has been replaced by cost effective modified carbon hole extraction layer. Herein, we demonstrated a new recipe toward air stable and waterproof modified carbon hole extraction layer for efficient perovskite solar cells (PSCs). The commercial available carbon ink modified with methylammonium lead iodide (MAI) has been used as hole extraction layer for ambipolar perovskite solar cells. The fabricated optimized perovskite solar cell having Glass/FTO/mp-TiO₂/MAPbI_3-xCl_x/carbon + MAI/Carbon configuration exhibited η = 13.87% power conversion efficiency (PCE) with open circuit voltage (V_OC) 0.997 V, current density (J_SC) = 21.41 mAcm^?2 and fill factor (FF) 0.65. Furthermore, the air stability were tested at room temperature in open atmosphere. The water proof stability was tested under water flushing. Our results revealed that, although our carbon based devices show lower PCE (η = 13.87%) compared to spiro-MeOTAD HTM (η = 15%), the fabricated PSCs could even retain >90% after water exposure >20 times and ambient air stability more than 160 days. Further the large area device (>1 cm²) device shows 13.04% PCE with Jsc = 21.47 mAcm^?2, V_OC = 0.996 V and FF = 0.61. We have also demonstrated >13% efficiency for large area device (>1.1 cm²), demonstrating that the developed method is simple, cost effective and promising towards large area device fabrication. The developed methodology based on low cost carbon hole extraction layer will be helpful towards waterproof and air stable perovskite solar cells for large-area devices.