Distinctive Deep-Level Defects in Non-Stoichiometric Sb₂ Se₃ Photovoltaic Materials

Characterizing defect levels and identifying the compositional elements in semiconducting materials are important research subject for understanding the mechanism of photogenerated carrier recombination and reducing energy loss during solar energy conversion. Here it shows that deep-level defect in antimony triselenide (Sb₂ Se₃ ) is sensitively dependent on the stoichiometry. For the first time it experimentally observes the formation of amphoteric Sb_Se defect in Sb-rich Sb₂ Se₃ . This amphoteric defect possesses equivalent capability of trapping electron and hole, which plays critical role in charge recombination and device performance. In comparative investigation, it also uncovers the reason why Se-rich Sb₂ Se₃ is able to deliver high device performance from the defect formation perspective. This study demonstrates the crucial defect types in Sb₂ Se₃ and provides a guidance toward the fabrication of efficient Sb₂ Se₃ photovoltaic device and relevant optoelectronic devices.