Effect of polymer nanolayers on tin-chalcogenide nanosheet/conductive polymer flexible composite films and their enhanced thermoelectric performance

The chemical exfoliation of SnSe0.97Te0.03 nanosheets is performed via a solid-state reaction, ball-milling, lithium intercalation, and a hydrothermal exfoliation reaction from atomic materials, and the potential of flexible thermoelectric composite films for practical applications is demonstrated. The exfoliated SnSe0.97Te0.03 nanosheets are very thin, ∼300 nm in lateral size, and coated with nanosize poly(3,4-ethylenedioxythiophene) (PEDOT), which exhibits great affinity to the PEDOT:PSS matrix compared with the SnSe0.97Te0.03 nanosheets without PEDOT coating. The enhanced thermoelectric performance can be explained by the fact that the PEDOT nano-coating on the surface of the SnSe0.97Te0.03 nanosheets contributes to the excellent distribution of the SnSe0.97Te0.03 nanosheets in the composite system. The thermoelectric performance is also enhanced with the increase of the PEDOT-coated SnSe0.97Te0.03 nanosheets, and a PEDOT-coated SnSe0.97Te0.03 nanosheet/PEDOT:PSS composite with 20 wt% of PEDOT-coated SnSe0.97Te0.03 nanosheets exhibits a maximum figure of merit (ZT) of 0.18, which is ∼61% higher than that of the composite sample without the PEDOT coating process. The results provide a promising strategy for inorganic/organic composite-based efficient thermoelectrics.