Poly(aniline-co-o-toluidine):poly(styrene sulfonic acid) nanocolloidal self assembled multilayer thin films as a hole transport layer in organic solar cells

A copolymer, poly(aniline-co-o-toluidine):poly(styrene sulfonic acid) has been synthesized and used as a hole transport layer in polymer solar cells based on poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester. The water dispersible nanocolloidal particles were characterized by Fourier transform infrared spectroscopy, UV–visible spectroscopy, particle size analyzer and transmission electron microscopy. The nanocolloidal solution has been spin coated on the substrate and layer by layer a self-assembly technique has used to form multilayer thin films. The optical and structural properties of self-assembled multilayer thin films were characterized by UV–visible, photoluminescence, X-ray diffraction and atomic force microscopy. The investigation of current–voltage characteristics of the polymer solar cells has revealed that the inclusion of the hole transport layer improves the photovoltaic performance. The current density of the device has been improved by the number of layers of the nanocolloidal copolymer.