Role of Formamidinium (FA)In the Electronic and Thermodynamic Properties of MA(Pb: Sn)I3Perovskites Using First Principle Calculations

Abstract

Research on perovskite solar cells employing tin to replace or partially replace lead is becoming morepopular because ofthe recent achievement of about 24.2% conversion efficiency for ecologically benign mixed Pb-Sn perovskite solar cells. However,a smaller effect on cohesive energies caused by the addition of a Sn metal has a considerable effect on thermodynamic properties of Pb-Sn perovskitesunder high-temperature effects. Thispaper investigates the roleof formamidiniumin the electronic and thermodynamic propertiesofMA(Pb: Sn)I3perovskite alloy using density functional theoryand CASTEP analysis through the Materials Studio. The intended A-cation perovskites have typical compounds FAxMA1-xSn0.5Pb0.5I3, where x=0, 0.2, 0.4 and 0.6.The control and FA-based perovskites were computed through CASTEP analysis from Material studio todetermine the electronic and thermodynamic properties. The findings revealed an improved thermodynamic properties of FA added perovskitescompared to control oneswhereby no significant effect was found in band gap of MAPb0.5Sn0.5I3 perovskite due to addition of formamidinium.However, when x is above 0.5, the quality of the perovskite filmsdeclined, with a wide grain size dispersion and little crystallization as well asthe phase impuritieswere detected. This necessitated a theoretical approach to achieve an optimum amount of FA additive required to improve the properties as well as providing a theoretical guidance for improving the properties of perovskite materials before carrying out experiments. Furthermore, the study predictsthat itispossible to create a stablethermalMA(Pb:Sn)I3alloy, ifthere isa well-thought-out design, which lays a foundation for the development and application of tin-lead mixed perovskite devices