Hydrogen-bonding-facilitated dimethylammonium extraction for stable and efficient CsPbI3solar cells with environmentally benign processing

Inorganic cesium lead triiodide perovskite has shown great potential in photovoltaic applications. Currently, the preparation of high-quality β- or γ-phase CsPbI3films largely relies on the DMAPbI3(dimethylammonium [DMA]) or “HPbI3”-assisted crystallization method, which unfortunately causes DMAPbI3residue and deteriorates photovoltaic performance and stability. Herein, a universal hydrogen-bonding-facilitated DMA extraction method is developed to fabricate high-quality γ-CsPbI3films. Theoretical and experimental evidence manifests that the hydrogen bonds formed between polyacrylic acid (PAA) and DMAPbI3decrease the DMA escape energy barrier, and this not only brings ahead the decomposition process of DMAPbI3but also accelerates the crystallization kinetics of CsPbI3, resulting in pinhole-free CsPbI3films without any trace of DMAPbI3residue and an extended fabrication humidity (up to 80% relative humidity [RH]) and temperature window. Thanks to the environmentally benign crystallization, the CsPbI3solar cells with dopant-free poly(3-hexylthiophene) (P3HT) yield a high efficiency of 20.25% and superior moisture and operational stability.