Investigation on Carrier Mobility when Comparing Nanostructures and Bands Manipulation

Nanostructuring as an effective strategy to reduce thermal conductivity was well developed to enhance thermoelectric performance in the past decades. However, electrical transport properties are always suppressed with nanostructures incorporated into a matrix, which finally causes limited increase of thermoelectric performance. To pursue further enhancement in thermoelectric materials beyond nanostructures, the approach of manipulating electronic band structures was revisited to optimize carrier transports by balancing the competitive relationship between carrier mobility and effective mass. In this review, we highlight and compare some advanced strategies to optimize electrical transport properties in lead and tin chalcogenides, including nanostructuring, bands manipulation and an integration of the two. We first summarize recent developments and compare the thermoelectric performance achieved by nanostructuring and bands manipulation, respectively. Then, several strategies to manipulate band structures are introduced and the competitive relationship between carrier mobility and effective mass are comprehensively investigated and revealed. Finally, the importance of elaborately modulating the carrier mobility and effective mass is emphasized, and a discussion of possible future strategies is presented to aim at further enhancing the thermoelectric performance.