The present invention relates to a layer system (1) for thin-film solar cells and solar modules based on CIS-absorbers (4). The layer system (1) according to the invention has a buffer layer (4) made of In2(S1−x,Sex)3+δ, wherein 0≦x≦1 and −1≦δ≦1. Additionally, the buffer layer (5) is amorphously designed. With this buffer layer (5), the disadvantages of CdS-buffers frequently used to date, namely toxicity and poor process integration, are overcome, whereby in addition to high efficiency, high long-term stability is also achieved; and thus again the disadvantages of conventional buffer layers alternative to CdS do not exist.