The influence of localized states on the optical absorption and carrier transport properties of acylamino hybrid perovskites with tunable electronic structures

Abstract

Organic-inorganic hybrid perovskite solar cells have excellent optoelectronic properties, but their low thermal and chemical stabilities limit their commercial applications. In this paper, a new type of organic-inorganic hybrid perovskite is proposed. Malondiamide (MA,CH2(CONH2)2) and propionamide (PA, CH3CH2CONH2) were used as organic layers, with Pb-I octahedral inorganic layers to form quasi three-dimensional (3D) perovskites. The crystal structure, stability, electronic structure, and optical properties of MAPbI4 and PAPbI4 perovskites were investigated, and the results showed that there were localized states that corresponded to the number of acyl groups in the two perovskites. Energy band calculations showed that the localized states of the two perovskites rose above the bottom of the conduction band. This can be used to regulate the band gap of the two perovskites, which affects the electronic properties and optical absorption characteristics of the two perovskites. Compared with PAPbI4, MAPbI4 has a lower formation energy, lower band gap, lower effective mass of electrons and holes, wider energy range, and larger absorption coefficient, which indicates that MAPbI4 is more suitable for use in solar cells. This study provides guidance for obtaining efficient and stable photovoltaic materials.