Impedance spectroscopy of Sb 2 Se 3 photovoltaics consisting of (Sb 4 Se 6 ) n nanoribbons under light illumination.

Sb 2 Se 3 , consisting of one-dimensional (Sb 4 Se 6 ) n nanoribbons has drawn attention as an intriguing light absorber from the photovoltaics (PVs) research community. However, further research is required on the performance-limiting factors in Sb 2 Se 3 PVs. In this study, we investigated the charge carrier behavior in Sb 2 Se 3 PVs by impedance spectroscopy (IS) under light illumination. (Sb 4 Se 6 ) n nanoribbons with two different orientations were used to investigate the effect of crystal orientation on the device performance. Regardless of the (Sb 4 Se 6 ) n orientation, negative capacitance was observed at forward bias, representing a recombination pathway at the TiO 2 /Sb 2 Se 3 interface. A comparison of the recombination resistances and lifetimes of two different Sb 2 Se 3 PVs showed that a better interface could be formed by placing the (Sb 4 Se 6 ) n ribbons parallel to the TiO 2 layer. Based on these observations, an ideal structure of the Sb 2 Se 3 /TiO 2 interface is proposed, which will enhance the performance of Sb 2 Se 3 PVs toward its theoretical limit.