Understanding the effect of surface chemistry on charge generation and transport in poly (3-hexylthiophene)/CdSe hybrid solar cells.

For hybrid solar cells, interfacial chemistry is one of the most critical factors for good device performance. We have demonstrated that the size of the surface ligands and the dispersion of nanoparticles in the solvent and in the polymer are important criteria in obtaining optimized device performance. The size of the ligands will affect the charge transport at the particle/particle and particle/polymer interfaces and the chemical structures of the ligands will determine their compatibility with the solvent and polymer. Hence other than pyridine, 2-thiophenemethylamine also showed good potential as ligand replacement for poly(3-hexylthiophene)/CdSe hybrid solar cells. With the right ligand combination, we have shown that the power conversion efficiency improved by a factor of 6 after ligand exchange.