Influence of Halides on the Interactions of Ammonium Acids with Metal Halide Perovskites.

Additive engineering is a common strategy to improve the performance and stability of metal halide perovskite through the modulation of crystallization kinetics and passivation of surface defects. However, much of this work has lacked a systematic approach necessary to understand how the functionality and molecular structure of the additives influence perovskite performance and stability. This paper describes the inclusion of low concentrations of 5-aminovaleric acid (5-AVA) and its ammonium acid derivatives, 5-ammoniumvaleric acid iodide (5-AVAI) and 5-ammoniumvaleric acid chloride (5-AVACl), into the precursor inks for methylammonium lead triiodide (MAPbI) perovskite and highlights the important role of halides in affecting the interactions of additives with perovskite and film properties.