Doping of Sn-based two-dimensional perovskite semiconductor for high-performance field-effect transistors and thermoelectric devices

Doping is an important technique for semiconductor materials and devices, yet effective and controllable doping of organic-inorganic halide perovskites is still a challenge. Here, we demonstrate a facile way to dope two-dimensional Sn-based perovskite (PEA)₂SnI₄ by incorporating SnI₄ in the precursor solutions. It is observed that Sn⁴⁺ produces p-doping effect on the perovskite, which increases the electrical conductivity by 10⁵ times. The dopant SnI₄ is also found to improve the film morphology of (PEA)₂SnI₄, leading to reduced trap states. This doping technique allows us to improve the room temperature mobility of (PEA)₂SnI₄ field-effect transistors from 0.25 to 0.68 cm² V^-1 s^-1 thanks to reduced trapping effects in the doped devices. Moreover, the doping technique enables the characterization and improvement of the thermoelectric performance of (PEA)₂SnI₄ films, which show a high power factor of 3.92 μW m^-1 K^-2 at doping ratio of 5 mol %.