Advances in n-type Bi2O2Se thermoelectric materials: Progress and perspective

Thermoelectric technology has been an alternative for waste heat recovery due to its ability to realize direct conversion between heat energy and electricity. As a promising n-type thermoelectric material, layer-structured Bi2O2Se has been widely investigated in the past decades. Bi2O2Se has excellent merits including extremely high carrier mobility, large Seebeck coefficient, low lattice thermal conductivity, low cost, as well as good thermal and chemical stability. Up to now, reviews especially regarding Bi2O2Se-based thermoelectric material are rare. Hence, in this review, the pristine features of Bi2O2Se as a thermoelectric material were systematically summarized from crystal structure and microstructure, electronic band structure, as well as phonon spectra. Then, the recent advances in optimization strategies for Bi2O2Se were updated and discussed, which were categorized into effective doping, texturing by shear exfoliation, and compositing with other materials. In the end, the current challenges and possible perspectives were highlighted toward further developments of Bi2O2Se.