Wait-time effects in CIGS PV module production

In this paper we present results of efficiency optimizations in conjunction with improved CIGS interface control. During large area thin film growth, understanding and control of the interfaces is an important key to enable a stable production. Our results indicate that efficiency, and weak light performance of CIGS modules can be increased and stabilized if wait time management and the related surface processes were better understood and controlled. The experiments indicate that oxide formation impacts the Na diffusion and has an impact on the module voltage. On the other hand defect formation before the absorber is observed to generate shunts between back contact and transparent conducting oxide with a significant drawback on the fill factor. Furthermore we show that internal sodium control helps to decouple wait times from module efficiency.