Efficient and Stable Self‐Powered Hybrid Perovskite Photodetectors Enabled by Additive Engineering via Easily Accessible Cross‐Linkable Zwitterionic Molecules

Abstract Organic‐inorganic hybrid perovskite materials have gained substantial research attention in the field of photodetectors (PDs) due to their remarkable optoelectronic properties and cost‐effective fabrication process. However, their performance and stability are often limited by the defects on the surface and/or at the grain boundaries of perovskite film. Herein, two zwitterionic molecules, [2‐(methacryloyloxy)ethyl]dimethyl‐(3‐sulfopropyl)ammonium hydroxide (DMAPS) and 3‐[bis[2‐(methacryloyloxy)ethyl](methyl)ammonio]‐1‐propanesulfonate (BDMAPS) are introduced, as processing additives for perovskite materials. Since DMAPS and BDMAPS contain both negatively and positively charged moieties, they can provide excellent effectiveness for defect passivation. Additionally, their vinyl groups participate in in‐situ cross‐linking reactions under mild reaction conditions, enabling the formation of 3D polymer passivation network that strengthens the structural integrity of the perovskite. Importantly, owing to the higher cross‐linking density of BDMAPS, perovskite PDs (PPDs) with BDMAPS additive exhibit improved device performance, achieving a specific detectivity of 1.50 × 10 ¹⁴ Jones and a responsivity of 0.52 A W ⁻¹ , which represents the highest reported value to date for self‐powered PPDs. Very encouragingly, the unencapsulated PPDs with BDMAPS additive exhibit excellent shelf‐stability even under high humidity conditions. This work highlights the potential of additive engineering in achieving efficient and stable PPDs, paving the way for the commercialization of next‐generation PDs technology.