Small molecule bulk heterojunction organic solar cells with coumarin-6 as donor material

To leverage the potential of organic solar cells, suitable materials for the photoactive layers have to be found. Herein, we show that the well-known fluorescent dye 3-(2?-benzothiazolyl)-7-diethylaminocoumarin works as an efficient light absorber material with a sensitivity at wavelengths from 400 to 650 nm. In combination with doped transport layers and optimization of the photodiode stack, a power conversion efficiency up to 1.9% under air mass 1.5 and 100 mW/cm2 illumination could be achieved.