High‐Performance Solution‐Processable Flexible SnSe Nanosheet Films for Lower Grade Waste Heat Recovery

Abstract Lower grade waste heat recovery near room temperature is limited due to multiple technology challenges including low efficiency, high cost, and scalability. Here, a low‐cost and scalable solution process is reported to fabricate a nanostructured SnSe thin film, and a high thermoelectric performance near room temperature is demonstrated. This transport study reveals strong phonon scattering near the interfaces between SnSe nanosheets that introduces a large thermal boundary resistance and an ultralow thermal conductivity of 0.09 W m −1 K −1 . Moreover, it is demonstrated that the SnSe thin film can be readily implemented on flexible plastic substrates and preserve the high thermoelectric performance over 1000 bending cycles. Together, this study demonstrates a low‐cost and scalable approach to achieve high‐performance flexible thin film energy harvesting devices to power electronics and sensors near room temperature.