Nano-scale morphology dependent performance of thin film organic solar cells

Polymer-fullerene based thin film organic solar cells (TFOSC) composed of poly(3-hexylthiophene) donor and [6,6]-phenyl-C61-butyric acid methyl ester electron acceptor are investigated with and without different processing additives such as: 1,8-diiodooctane (DIO), 1-chloronaphthalene and dimethyl sulfoxide (DMSO). The effect of these solvents on device performance has been investigated and discussed in terms of changes in optical, electrical and microstructural properties of the photoactive films. Among the additives used in this study DIO has shown remarkable effect on preventing the formation of defect related clusters in the medium and assists the crystallization of the polymer chain leading to the best device performance in the investigation. The nanoscale structures of the films produced with DMSO showed the presence of large concentration of defect clusters resulting in poor performance. Various results of TFOSC devices with and without solvent additives are compared and thoroughly discussed.