Although polymer materials possess the advantages such as low cost and easy fabrication of flexible and large-scale film for the application in photovoltaic devices, the performance of polymer-based solar cells, especially energy conversion efficiency is inferior to their inorganic counterpart due to the shorter charge diffusion length caused by the comparatively lower electric field between the electrodes. This paper reviewed the strategies to improve their photovoltaic properties mainly concentrated on modifying the polymer materials and ameliorating the device configuration. First, polythiophene (PT), poly(phenylene vinylene) (PPV), polyfullerene, and other novel polymer materials were introduced and the effective ways to modify their derivatives with more advantages were described in detail, for instance, copolymerization, incorporating additives and dyes, etc. Furthermore, the content of ameliorating the device configuration encompassed on inverted architecture, tandem structure, the introduction of buffer layers, thermal annealing, and the integration of optimized conditions. Finally, the effects of the improvement methods were concisely summarized, and the perspectives of the future research were put forth.
Research progress of cathode buffer layers of the polymer solar cells
