Thermoelectric Performance of Lead-Free Two-Dimensional Halide Perovskites Featuring Conjugated Ligands

Sn-based halide perovskites are promising for thermoelectric (TE) device applications because of their high electrical conductivity as well as the low thermal conductivity associated with their soft lattices. However, conventional three-dimensional Sn-based perovskites are not stable under typical TE device operating conditions. Here, we report a stable two-dimensional Sn-based perovskite for thermoelectric energy conversion by incorporating bulky conjugated ligands. We demonstrate a thin film with a large power factor of 5.42 ± 3.07 (average) and 7.07 (champion) μW m–1 K–2 at 343 K with an electrical conductivity of 5.07 S cm–1 and a Seebeck coefficient of 118.1 μV K–1. Importantly, these thin films show excellent operational stability (i.e., for over 100 h) at 313 K. This work suggests that the novel hybrid two-dimensional perovskites are a promising platform for thermoelectric energy conversion applications.