An exploration of the role of acetamidinium substitutionin methylammonium lead iodide perovskites

Abstract

Halide perovskite (HP) versatility for optoelectronic and electro-chemical applications is mainly due to their ability to engineercation mixtures at the A-site within the ABX3 stoichiometry.Acetamidinium (AC) is a common cation used in these mixedcompositions, but its effects on the material’s properties havenot been addressed in detail. In this work, prototypical methyl-ammonium lead iodide (MAPbI3 ) compositions partially substi-tuted with ACþ are synthesized and analyzed for structural,electrical, optoelectronic, and stability properties. Results reveala solubility limit of around 10% AC, lower than encounteredin the literature, with slight effects on the phase transitiontemperatures. As expected, substitution with AC significantlyreduces electronic conductivity and I–V hysteresis but only mar-ginally increases the bandgap energy. Contrary to literatureresults, light-accelerated degradation tests show that AC incor-poration does not significantly enhance the materials’ stability.Among several reasons, this might be related to weak interactionsbetween AC cations and the inorganic framework. This studyestablishes the effects of AC substitution in halide perovskitesand provides insights into optimizing A-site compositions foroptoelectronic and electrochemical applications.