A comparative study of Cd- and Zn-compound buffer layers on Cu(In1-x,Ga-x)(S-y,Se1-y)(2) thin film solar cells

摘要

This paper reports a comparative study of Cu(In,Ga)(S,Se)(2) (CIGSSe) thin-film solar cells with CBD-CdS, CBD-ZnS(O,OH) and ALD-Zn(O,S) buffer layers. Each buffer layer was deposited on CIGSSe absorber layers which were prepared by sulfurization after selenization (SAS) process by Solar Frontier K. K. Cell efficiencies of CBD-CdS/CIGSSe, CBD-ZnS(O,OH)/CIGSSe and ALD-Zn(O,S)/CIGSSe solar cells exceeded 18%, for a cell area of 0.5cm(2). The solar cells underwent a heat-light soaking (HLS) post-treatment at 170 degrees C under one-sun illumination in the air; among the three condtions, the ALD-Zn(O,S)/CIGSSe solar cells showed the highest cell efficiency of 19.78% with the highest open-circuit voltage of 0.718V. Admittance spectroscopy measurements showed a shift of the N-1 defect's energy position toward shallower energy positions for ALD-Zn(O,S)/CIGSSe solar cells after HLS post-treatment, which is in good agreement with their higher open-circuit voltage and smaller interface recombination than that of CBD-ZnS(O,OH)/CIGSSe solar cells. Copyright (c) 2015 John Wiley & Sons, Ltd.