Large-area Cd-free CIGS solar modules with In2S3 buffer layer deposited by ALCVD

The development of Cd-free buffer layers by vacuum process for Cu(In,Ga)Se 2 (CIGS) solar modules becomes even more interesting regarding environmental aspects and the implementation in industrial production. This work presents the latest results of CIGS modules with indium sulfide (In 2 S 3 ) as buffer layer deposited by the atomic layer chemical vapour deposition technique. A module efficiency close to 13% was realised on the area of 30x30 cm 2 (η=12.9%, V OC =27,8 V, FF=72.6%, I SC =0.457 A, aperture area: 714 cm 2 and 42 cells). Diffusion processes at the buffer layer interfaces, dependent on deposition temperature and post annealing, have been investigated by X-ray photoelectron spectroscopy, secondary ion mass spectrometry and sputtered neutral mass spectrometry analysis. Diffusion of Cu and Na into the buffer layer and intermixing of S and Se at the In 2 S 3 /CIGS interface have been detected.