Enhanced stability of perovskite solar cells using hydrophobic organic fluoropolymer

Hydrophobic organic fluoropolymers (HOFPs) with excellent hydrophobic, heat-resistant, and sunlight-transparent properties were synthesized by emulsion polymerization. The HOFP layer was inserted between a (FAMA)Pb(IBr)3 active layer and a hole transport layer in perovskite solar cells (PSCs). The performance of the resulting PSC devices depends highly on the thickness of the HOFP layer. Under optimized HOFP thickness, a moderate steady power conversion efficiency (PCE) of 16.9% was achieved. Remarkably, the optimized PSCs without any encapsulation exhibit outstanding shelf stability under ambient conditions, and the PCE could maintain 80% of its initial value after 2400 h (100 days), which was among the ever reported best stability whereas, the reference device without HOFP shows rapid severe degradation after only a few days. The significantly improved stability of PSCs was mainly ascribed to the impermeable barrier properties of the HOFP layer, which protect the perovskite active layer against moisture...