Role of proton conducting polyelectrolyte on the organic photovoltaics efficiency

Most of the efficient organic solar cells (OSC) often utilize reactive low-work-function metals like calcium and LiF as a buffer layer. Over a period of time, these types of buffer layer degrade, reacts and diffuses into electrode, photoactive layer. These type of changes results in reduction in efficiency and less lifetime of the OSC. This work demonstrated fabrication of OSC with ionic conducting non-conjugated polyelectrolytes polyethyleneimine (PEI) and perfluorinated ionomer (PFI) instead of conventional transport layer. PEI and PFI were used as a cathode and anode buffer, respectively, in the following device configuration ITO/PEI/P3HT:PC₆₁BM/PFI/Ag. For various PFI thickness, OSC efficiency was optimized. The highest efficiency of 1.82% was obtained for 1:15 PFI ratio device, which was significant improvement than the reference device without PFI. The obtained results were analyzed and critical changes were discussed in this work.