Structural and Electronic Properties of Inorganic Mixed Halide Perovskites

In this work, we investigate the structural and electronic variations of all‐inorganic mixed halide perovskites CsPb(Cl 1− x Br x ) 3 and CsPb(Br 1− x I x ) 3 upon their halide composition, by the first‐principles calculation with the spin–orbit interaction. We find that these perovskites always keep their direct‐bandgap nature, even though structurally their PbX 6 octahedra are more or less distorted with different halide ratios (Cl/Br or Br/I). Their optical bowing parameters show no dependence on such composition ratios, which means their bandgaps can be linearly tuned. Moreover, these perovskites also exhibit rather good bipolar transport character, as both electrons and holes have the effective masses of less than 0.2 m 0 . Therefore, we propose that by properly tuning the halide composition ratio, these mixed halide perovskites can be fabricated into light‐emitting devices with selected frequency in a broad frequency range.