1. Fitting Murnaghan equation of state to obtain the equilibrium volume and bulk modulus with inset showing the atomic structure of γ-phase CsPbI₃

2. Band structures of γ-CsPbI₃ calculated by two hybrid functionals HSE-0.43 (a) and PBE0-0.2 (b) including the SOC effect

3. Atomic structures of 12 intrinsic defects after relaxation in neutral charge stateAs two functionals yield similar structures, only the structures from PBE0-0.2 calculations are shown here

4. Defect transition levels in γ-CsPbI₃ calculated by HSE-0.43 (a) and PBE0-0.2 (b)Blue lines: acceptor levels; Red lines: donor levels

5. Kohn-Sham energy levels of v_Cs, v_I, Cs_i, I_i, Cs_Pb and Pb_Cs defects calculated by HSE-0.43 (a) and PBE0-0.2 (b)For acceptor defects, the left half is for −1 state, while the right half is for the neutral state. For donor defects, the left half is for neutral state, while the right half is for +1 state. Open and solid circles represent holes and electrons, respectively.

S1. Total and projected density of states of γ-CsPbI₃ calculated by two hybrid functionals HSE-0.43 (a) and PBE0- 0.2 (b) including the SOC effect

S2. Parabolic fitting of the band near Γ point to obtained the effective masses of electrons and holes.For clarity, the electron and hole bands are referenced to the CBM and VBM, respectively; SOC effect is included here; (a) HSE-0.43; (b) PBE0-0.2

S3. Comparison of dielectric constants calculated by two hybrid functionals(a) Real part ε₁; (b) Imaginary part ε₂; Calculations considered SOC effect and employed 5×4×5 k-grid and 544 empty bands