Organic small molecule solar cells with a homogeneously mixed copper phthalocyanine: C60 active layer

An efficient organic solar cell with a vacuum codeposited donor–acceptor copper phthalocyanine (CuPc):C60 mixed layer is described. A device with a structure of indium tin oxide/330 Å CuPc:C60(1:1)/100 Å C60/75 Å 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline/Ag has a series resistance of only RS=0.25 Ω cm2, resulting in a current density of ∼1 A/cm2 at a forward bias of +1 V, and a rectification ratio of 106 at ±1 V. Under simulated solar illumination, the short circuit current density increases linearly with light intensity up to 2.4 suns. The maximum power conversion efficiency is ηP=(3.6±0.2)% at 0.3 suns (AM1.5G simulated solar spectrum) and ηP=(3.5±0.2)% at 1 sun. Although the fill factor decreases with increasing intensity, a power efficiency as high as ηP=(3.3±0.2)% is observed at 2.4 suns intensity.