Manipulating Nucleation and Crystal Growth of Inorganic Perovskite Solar Cells

Inorganic metal halide perovskite materials as sunlight absorbers for solar cells exhibit better thermal stability than organic-inorganic hybrid counterparts. Pure cesium lead triiodide (CsPbI3), with the most suitable band gap, suffers phase instability under an ambient environment. Nucleation and crystal growth are two crucial steps in fabricating a solution-processed perovskite film. A high-quality perovskite film with good morphology makes a significant impact on the efficiency and stability of perovskite solar cells. Dimethylformamide (DMF) is a commonly used aprotic solvent. However, it is difficult to obtain a high-quality inorganic perovskite film using DMF as a single solvent due to its slow evaporation and strong coordination with Pb2+. Here, we investigate dimethylacetamide (DMAc)/DMF as a cosolvent to prompt nucleation during the spin-coating process, leading to higher nucleation density and better surface coverage. In addition, we introduce CsBr in dimethylammonium lead triiodide (DMAPbI(3))/CsI precursors to slow down the crystal growth process. CsBr does not increase the film band gap but leads to a pinhole-free film with better crystallinity. Through nucleation and crystal growth engineering, the power conversion efficiency of inorganic perovskite devices is improved to 17.67%, and ambient environment stability is significantly enhanced.

Automated summary

Inorganic metal halide perovskite materials exhibit better thermal stability than organic-inorganic hybrid counterparts for solar cells. However, pure cesium lead triiodide suffers phase instability under ambient conditions. Nucleation and crystal growth are crucial steps in fabricating high-quality perovskite films, and their engineering can improve the efficiency and stability of perovskite solar cells. By using dimethylacetamide (DMAc)/DMF as a cosolvent to enhance nucleation and incorporating CsBr in DMAPbI(3)/CsI precursors to slow down crystal growth, the power conversion efficiency of inorganic perovskite devices is improved to 17.67% with enhanced stability.