High Carrier Mobility and Promising Thermoelectric Module Performance of N ‐Type PbSe Crystals

Optimizing carrier concentration is crucial for thermoelectric materials. Previous studies suggest an ideal range from ~1019 to ~1021 cm−3 (blue line). Yet, grain boundaries in polycrystals hinder carrier mobility. The authors propose enhancing mobility through crystal growth and light-doping at lower concentrations (from ~1018 to 1019 cm−3) for potentially elevated ZT values (red line). AbstractThe scarcity of Te hampers the widespread use of Bi2Te3-based thermoelectric modules. Here, the thermoelectric module potential of PbSe is investigated by improving its carrier mobility. Initially, large PbSe crystals are grown with the temperature gradient method to mitigate grain boundary effects on carrier transport. Subsequently, light doping with<1mole ‰ halogens (Cl/Br/I) increases room-temperature carrier mobility to ~1600 cm2 V−1 s−1, achieved by reducing carrier concentration compared to traditional heavy doping. Crystal growth design and light doping enhance carrier mobility without affecting effective mass, resulting in a high power factor ~40  µW cm−1 K−2 in PbSe-Cl/Br/I crystals at 300  K. Additionally, Cl/Br/I doping reduces thermal conductivity and bipolar diffusion, leading to significantly lower thermal conductivity at high temperature. Enhanced carrier mobility and suppressed bipolar effect boostZT values across the entire temperature range in n-type PbSe-Cl/Br/I crystals. Specifically,ZT values of PbSe-Br crystal reach ~0.6 at 300  K, ~1....
Source: Small - Category: Nanotechnology Authors: Tags: Research Article Source Type: research