Boosting Electron Extraction in Polymer Solar Cells by Introducing a N-Type Organic Semiconductor Interface Layer

摘要

Enhanced power conversion efficiency (PCE) is reported in inverted polymer solar cells (PSCs) when a high electron mobility molecular semiconductor of fluorinated copper phthalocyanine (F16CuPc) is employed on the top of the poly(ether imide) (PEI) buffer layer. The thickness of the F16CuPc and PEI is rearranged to shield the insulating effect of PEI and enhance the electronic coupling between the hydrophobic inorganic ITO and hydrophilic organic active layer. The results demonstrate that the enhanced PCE is attributed to the improved forward charge transfer and the contact resistance decrease by passivating interfacial trap states and defects of ITO surface. The hydrophilic F16CuPc interlayer also regulates the upper organic layer growth mode and morphology so that the back charge recombination is noticeably decreased. As a result, the optimized PSCs indicate the improved PCE of 9.516% relative to 7.147% of the device without F16CuPc.