Preparation and characterization of pulsed laser deposited Sb2Te3 back contact for CdTe thin film solar cell

A low electric resistive and stable ohmic back contact are crucial to the commercial application of CdTe solar cells. In this study the Sb2Te3 thin film is employed as a buffer layer in the back contact of CdTe solar cells. The Sb2Te3 thin films are deposited at different substrate temperature by pulsed laser deposition and then characterized to investigate the thin film properties, firstly. Hall measurements shows the Sb2Te3 thin film presents strong p-type semiconductor features with high Hall mobility and carrier concentration. CdTe solar cells with Sb2Te3 buffer layer in different layer thickness and deposition temperature are fabricated to obtain the optimal experiment conditions for device performance. The dark J-V curve of CdTe solar cell with Sb2Te3 buffer layer exhibits a typical diode curve without roll-over phenomenon. An insertion of Sb2Te3 buffer layer eliminates the Schottky barrier resulting in remarkable enhancement of open circuit voltage, short-circuit current and fill factor. Besides, the external quantum efficiency gets improvement in almost all of the absorber wavelength compared to the cells with Au-only contact.