High photovoltaic efficiency CZTSSe thin film solar cells obtained by Li doping in air

Alkali metal doping is considered as an effective strategy in the pathway of improving the efficiency of Cu2ZnSn (S,Se)4 (CZTSSe) photovoltaic materials. In this paper, Li is successfully doped into CZTSSe films in air and high efficiency devices are obtained. By X-ray diffraction and scanning electron microscopy, it can be found that the crystalline quality of CZTSSe films after Li doping is effectively improved and full and dense absorber layer crystals are obtained. In addition, TRPL also shows that the carrier lifetime of CZTSSe by doping with Li is significantly enhanced. Lithium-doped CZTSSe thin-film solar cells finally achieve a high efficiency of 9.84%. This Li doping route with simple process and superior device performance obtained provides a new idea for further development of element-rich and non-toxic CZTSSe thin film materials.