Nanoscale phase-aggregation-induced performance improvement of polymer solar cells

Nanoscale aggregation of fullerene (C₆₀) induced by its crystallization upon thermal treatment provides improved morphology for the photoactive layer. The electron donor-acceptor approach is the most successful method to make photoinduced excitons split into free charge carriers, which are collected by the corresponding electrodes and give photovoltaic electricity. The formation of nanoscale C₆₀ single crystals and their homogeneous distribution in the photoactive layer provide a continuous pathways for electron transportation to the cathode, which could decrease the recombination procedure. Nanoscale aggregation of acceptor C₆₀ in the composite film helps in improving the performance of the electron donor P3HT/C ₆₀ device. In polymer solar cells based on a mixture consisting of conjugated polymer and organic small-molecule constituents, small molecules form clusters and provide continuous pathways for the transportation of free charge carriers throughout the film.