High-Temperature Degradation Mechanism of Cu(In,Ga)Se₂-Based Thin Film Solar Cells

Abstract

The degradation mechanism of Cu(In,Ga)Se2 (CIGS) thin film solar cells under high-temperatures conditions has been investigated. CIGS thin film solar cells were heated at temperatures ranging from 100 to 450 °C in a vacuum for 30 min. It was found that the CIGS devices with chemical bath deposited (CBD)–CdS and CBD–ZnS(O,OH) buffer layers were stable below 320 and 350 °C, respectively. These results suggest that CIGS devices possess high heat-resistance enough for practical usage. Secondary ion mass spectrometer (SIMS) and electron beam induced current (EBIC) analyses revealed that the main cause for the degradation of CIGS devices at high temperatures is attributable to a shift of the space charge region (SCR) toward the Mo back contact due to excess diffusion of Cd into CIGS absorber layer.