Efficient thin-film solar cells prepared by a sequential process

Abstract

-based thin-film solar cells are presented with 11.1% total area efficiency or 12.5% active area efficiency. This is the best efficiency reported so far for this type of solar cell. The technology is based on a sequential process using d.c. magnetron sputtering of the metals and sulphurization in elemental sulphur vapour without the use of a toxic gas. Absorber layers and solar cells with precursor atomic copper to indium ratios between 1.0 and 1.8 are analysed. The best cells with fewest defects are made from the most copper-rich CuIn precursor layers. The solar cell performance, however, decreases only slowly for small deviations of the Cu/In ratio from the optimum value.