Enhanced carrier transport in CsxSnBry perovskite by reducing electron-phonon coupling under compressive strain

Low-toxicity and environmentally friendly tin-based perovskite materials are attractive substitutes for lead halide perovskites in photovoltaic and optoelectronic devices. However, the polar perovskite lattice coupled with charge carrier, and strong polar optical phonon scattering severely affect the carrier transport. Here, we perform the first-principles calculation, and demonstrate that the carrier mobility can be significantly enhanced by applying compressive strain to the lattice, which can be attributed to the reduction of the electron-phonon coupling. Pressure-induced electron-phonon coupling strength evolutions correlate well with the polar optical phonon scattering changes. The maximum carrier mobility is 11 cm2 V−1s−1 and 143 cm2 V−1s−1 of Cs2SnBr6 with the unstrained and strained structure (13 % compression). The carrier mobility of CsSnBr3 with 1 % compression is improved due to a significant dielectric response induced by the dynamic lone pair activity of CsSnBr3. These studies indicate that compressive strain can significantly alter the structure and carrier transport characteristics of tin-based perovskite materials, which are important for photovoltaics and optoelectronics.