Influence of source temperature upon the contamination with cu of thin-film CDTE solar cells grown by close space sublimation technique

Abstract

Photoconversion efficiencies up to 16.5 % have been attained from CdTe/CdS solar cells. CdTe/CdS heterojunction can be deposited cheaply over large areas using the close space sublimation (CSS) technique. In a previous study of CdTe/CdS thin film solar cells we have established that a post growth treatment involving deposition of CdCl2 and annealing in air at 400 oC increases the photovoltaic efficiency of the junction by two orders of magnitude. The stability issues are now of prime importance for future implementation of thin-film CdTe solar cells. The diffusion of Cu from the back contact represents the most suspected source of instability for CdTe/CdS solar cells. Another source of contamination with Cu during the CSS process is the source material containing a residual Cu impurity.