Pressure-Tunable Optimal Bandgap in 3D Halide Perovskites: A Study of APbI(3) (A=AM1, AM2, FM1, FM2, and DM)

Exploringnovel three-dimensional (3D) perovskite photovoltaicmaterials with high performance and optimal bandgap is an attractivestrategy for expanding the perovskite family and replacing the currentlywidely studied, unstable CH3NH3PbI3 perovskite materials. To achieve stable, 3D perovskite materialswith excellent performance, five small organic cations (AM1, AM2,FM1, FM2, and DM) were introduced into the A-site of ABX(3) perovskite. The geometric structure, thermodynamic stability, electronicproperties, and carrier transport properties of these materials wereinvestigated using first-principles calculations. Additionally, thebandgap tunability and structural stability of these materials underdifferent pressures were studied. The research results indicate thatthe replacement of different organic cations can produce highly stableperovskite phases with suitable direct bandgaps and smaller effectiveelectron and hole masses. Theoretical calculations demonstrate thatFMPbI(3)-1, FMPbI3-2, and DMPbI3 3Dorganic-inorganic hybrid perovskites exhibit excellent bandgapadjustability, and the optimal photovoltaic bandgap can be achievedthrough pressure tuning. Combined with large light absorption, smallexciton binding energy, high carrier mobility, and high power conversionefficiency, these materials are expected to achieve unique photovoltaicdevice performance and applications.