Computational design and properties elucidation of new (FAPbI3)1,x- y(MAPbBr3)y(CsPbBr3)x photoactive systems for their application in perovskite solar cells

The stability and performance of perovskites (PKs) in PK solar cells are a research target, which has been addressed in this work. The theoretical design of new PKs was carried out, based on the different composition of Cs. Specifically, PKs of the type (FAPbI3)1_x-y(MAPbBr3)y(CsPbBr3)x (where MA= methylammonium and FA= formamidinium) with 0 <x,y < 0.5 were proposed as sensitizers and photocurrent generators. The band gaps, effective masses, absorption spectra, and photocurrent properties of the PKs were investigated, to find an attractive candidate to be synthesized and employed in solar cells. The electronic properties were obtained using first principles calculation, including the spin-orbit coupling. As a remarkable result, it was analyzed that all systems might be used on solar devices according to the computed band gaps. Furthermore, the effective mass of charge carriers behaves relatively homogeneous in all the studied systems and is below the maximum required of 1.5 m0. In particular, compounds (FAPbI3)0.83(CsPbBr3)0.17 and(FAPbI3)0.64(MAPbBr3)0.17(CsPbBr3)0.17 stand out due to their panchromatic absorption spectrum nature and high current density (Jsc) values. Besides, the Jsc values for these compounds are two orders of magnitude greater than those calculated for the perovskite FAPbI3, which reaches efficiencies greater than 25%, hence we support them to be used in photovoltaic devices.