Interfacial defect passivation and improved crystallinity of $Sb_2Se_3$ thin film solar cells

Abstract

Low-toxic and earth-abundant $Sb_2Se_3$ binary compound consists of simple one dimensional crystal structure with suitable absorption coefficients, carrier mobility and bandgap for thin film solar cells, having drastic development of power conversion efficiency (PCE) from 1.9% in 2014 to 9.2% in 2019. At high temperature, $Sb_2Se_3$ decomposes into Se atoms which have high vapor pressure, increasing probability of $V_{Se}$ formation which was reported to have detrimental effect in chalcogenide-based thin films due to lowest defect formation energy. Improved carrier collection was predicted by efficient carrier transport when $Sb_2Se_3$ is aligned into c-axis orientation because electrical property of $Sb_2Se_3$ is strongly determined by crystallinity of unique one-dimensional ribbon structure. In this study, $Sb_2Se_3$ thin film solar cells were fabricated by vapor transport deposition (VTD) which is one of the fast vacuum deposition method. Interfacial defect passivation by oxygen incorporation and the growth as well as crystallinity of $Sb_2Se_3$ with different temperature of substrate and source will be discussed.