Advances in Thermoelectric Cu ₂ ZnSnS ₄ : From Structure, Synthesis to Performance

ABSTRACT

Thermoelectric technology has the capacity to directly convert waste heat into electricity and vice versa. For a long time, Cu ₂ ZnSnS ₄ (CZTS) has been extensively researched in the domains of solar cells and photocatalysis due to its exceptional photovoltaic properties, but its wide bandgap prevents it from being favored in thermoelectrics. Recently, advancements in wide‐bandgap thermoelectric materials have led to significant breakthroughs, and CZTS has garnered increasing interest owing to its low‐cost and environmentally friendly characteristics. To promote the further development of the emerging thermoelectric CZTS, this review has made a thorough summary, covering aspects from the crystal structure and preparation techniques to the electron and phonon transports. Firstly, we conduct an in‐depth investigation into the crystal structure, defect formation energy, and phase diagram to elucidate the thermodynamic stability and synthesis challenges associated with the single‐phase formation. Then, several typical CZTS preparation methods and their corresponding micro‐morphologies are summed up and compared, and the high‐quality crystal growth technology is introduced in detail for optimal thermoelectric performance. Furthermore, the electron and phonon transports in CZTS are discussed, with a comprehensive elaboration of their influence on thermoelectric performance. Finally, some possible valid strategies are proposed to aim at enhancing the figure of merit of CZTS to meet the demands of low‐cost, high efficiency, and environmental compatibility in future thermoelectric applications.