Multidentate anchoring through additive engineering for highly efficient Sb2S3 planar thin film solar cells

Sb 2 S 3 is a promising candidate for the flexible solar cells or the top subcells in tandem solar cells due to its wide-bandgap, less toxic, acceptable cost and progressive power conversion efficiency (PCE). However, the poor quality and high trap states of Sb 2 S 3 films limit the device performance further enhancement. Herein, we adopt a multidentate ionic liquid , tetramethylammonium hexafluorophosphate ([TMA][PF 6 ]) as a novel additive to address this issue. The octahedral [PF 6 ] − contains six different oriented fluorine atoms with the lone pair electrons , which could coordinate with Sb atoms due to the multidentate anchoring. Thus, the high-quality Sb 2 S 3 film with low trap states has been achieved. Moreover, the Fermi level of the Sb 2 S 3 film has been upshifted, thereby showing an effective charge transfer. As a result, all photovoltaic parameters of the optimized Sb 2 S 3 devices are obviously enhanced, boosting the final PCE from 4.43 (control device) to 6.83 %. Our study about the multidentate anchoring is manifested to be an effective method to enhance the Sb 2 S 3 device performance.