Tailoring interfacial states for improved n-type bismuth telluride thermoelectrics

Efforts to enhance the thermoelectric (TE) efficiency of n-type bismuth telluride (BTS) have focused on leveraging 2D nanostructures, as they have been proven effective in inhibiting phonon transport and simultaneously improving electrical properties. Herein, we introduce g-C3N4 as a suitable candidate for disrupting phonon transport, with the potential to finely tune charge carrier mobility. Crucially, our investigation provides insights into the potential of externally introduced conducting states as a feasible strategy for facilitating carrier transport at heterogeneous interfaces. In contrast, the carrier scattering and localization events play an inverse role. By carefully modulating the competition, we effectively increase carrier mobility, boosting electrical conductivity and optimizing the power factor. This orchestrated strategy leads to a high figure of merit (ZT) of 1.29 at 400 K and an average ZT (ZTave) of 1.20 within 300-500 K. At temperature difference ∆T = 180 K, a maximum power output Pmax = 0.91 W and a 6.2% conversion efficiency (η) can be achieved over the fabricated TE module. Our findings underscore the potential of 2D nanomaterials and interfacial engineering (IE) as a promising avenue for unlocking the full potential of n-type thermoelectric materials, advancing sustainable and efficient TE power generation.