High intrinsic carrier mobility and photon absorption in the perovskite CH3NH3PbI3
The carrier transport and optical properties of the hybrid organic–inorganic perovskite CH3NH3PbI3 are investigated using first-principles approaches. We found that the electron and hole mobilities could reach surprisingly high values of 7–30 × 103 and 1.5–5.5 × 103 cm2 V−1 s−1, respectively, and both are estimated to be much higher than the current experimental measurements. The high carrier mobility is ascribed to the intrinsically small effective masses of anti-bonding band-edge states. The above results imply that there is still space to improve the performance of related solar cells. This material also has a sharp photon absorption edge and an absorption coefficient as high as 105 cm−1, both of which contribute to effective utilization of solar radiation. Although band-edge states are mainly derived from the inorganic ions of Pb and I, thermal movement of the organic base has indirect influences on the bandgap and carrier effective masses, resulting in the temperature-dependent solar cell efficiencies.