Use of anti-solvent to enhance thermoelectric response of hybrid halide perovskite thin films

Abstract

Hybrid halide perovskite research has recently been focused on thermoelectric energy harvesting due to the cost-effectiveness of the fabrication approach and to the ultra-low thermal conductivity. To achieve high performance, tuning of the electrical conductivity is a key parameter that is influenced by grain boundary scattering and charge carrier density. The fabrication process allows the tuning of these parameters. We report the use of anti-solvent to enhance the thermoelectric performance of lead-free hybrid halide perovskite (CH3NH3SnI3) thin films. Thin films with anti-solvent show higher connectivity in grains and higher Sn+4 oxidation states which result in the enhancement of the value of electrical conductivity. The thin films were prepared by a cost-effective wet process. Structural and chemical characterizations were performed using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The values of electrical conductivity and the Seebeck coefficient were measured near room temperature. A high value of the power factor (1.55 μW m-1 K-2 at 320 K) was achieved for thin films treated with anti-solvent.