Efficient and stable hole-transporting-layer-free perovskite solar cells by introducing propionyl chloride passivator

Hole-transporting layer (HTL)-free perovskite solar cells (PSCs), due to their lower cost than HTL-contained PSCs, provide a cheap photovoltaic technology to meet global energy demands. Their low efficiency, albeit, is a critical obstacle to their industrialization. In the current study, we employed propionyl chloride material as an additive for the mixed-cation perovskite precursor to reduce the bulk and surface perovskite defects and consequently boost the device's photovoltaic performance. Results show that the propionyl chloride additive caused reduced trap density within light-harvesting perovskite and suppressed non-radiative losses in the photovoltaic device. In addition, propionyl chloride improved perovskite morphology by reducing surface defects, which hinder charge accumulation centers on the perovskite interface and facilitate charge transport mechanisms. The propionyl chloride-passivated perovskite offers a champion efficiency of 14.78%, higher than the efficiency of 12.29% recorded for control hole-transport layer-free PSCs. In addition, passivated perovskites showed higher resistance against ambient degradation due to their improved crystalline properties.