Influence of solvent on the molecular ordering of thin films of P3HT:PCBM blends and precursor solution

Optical and structural properties of thin films of P3HT:PCBM blends grown by spin coating using a wide variety of solvents were studied through different techniques such as x-ray diffraction (XRD), Raman spectroscopy and spectral absorbance. The study revealed that the use of mesitylene as solvent allowed to grow P3HT:PCBM blends with improved properties for use as active layer of organic cells with bulk heterojunction structure. It was also found that the evaporation rate of solvent, significantly affect the optical and structural properties of the P3HT:PCBM blends, apparently as a consequence of an improved ordering of the P3HT chains. The type of solvent and its concentration also affects the interaction between polymer chains of the materials in solution.