Abstract: A method for determining the quantum efficiency of a solar cell (11) comprising an active layer sequence (3) is specified, comprising the following steps: A) providing the active layer sequence (3) comprising at least one optoelectronically active layer (4, 5) which has an absorption spectrum; B) carrying out a plurality of measurements of photocurrents generated in the optoelectronically active layer (4, 5), wherein during the plurality of measurements, the photocurrents are generated by light having mutually different illumination spectra, the mutually different illumination spectra are differently weighted superimpositions of a plurality of individual spectra (50, 60) having respectively different characteristic wavelengths (51, 61), individual spectra (50, 60) having adjacent characteristic wavelengths (51, 61) overlap, and each of the different illumination spectra covers the absorption spectrum; C) determining the quantum efficiency from the plurality of photocurrents and the associated weighte