Enhancing Electroluminescence of Medium-Gap Organic Photovoltaic Cells Through the Incorporation of Pyrrole Rings in Acceptors

High electroluminescence of acceptors can effectively decrease nonradiative energy losses and improve the performance of organic photovoltaic (OPV) cells. Pyrrole ring is a promising building block to enhance the electroluminescence of acceptors, while pyrrole-based acceptors with medium bandgap are rarely reported. Here, two medium-gap acceptors named FICC-EH and FICC-BO are synthesized. Both acceptors exhibit strong electroluminescence properties, giving satisfying quantum efficiency (QE) of 0.1% in organic light-emitting diodes (OLEDs). Moreover, PBQx-TF:FICC-BO presents a longer film formation process due to the longer alkyl chains. This contributes to more distinct fibril-network morphology and ordered molecular stacking, thus increasing carrier mobility and suppressing charge recombination. Consequently, benefiting from decreased energy losses, PBQx-TF:FICC-BO-based OPV cells reach a PCE of 12.0% with a VOC of 1.04 V under AM 1.5G and achieve a PCE of 25.4% under 1000 lux LED. This work demonstrates the potential of pyrrole for constructing medium-gap acceptors with strong electroluminescence for photovoltaic applications. Two pyrrole-based medium-gap acceptors named FICC-EH and FICC-BO are synthesized, and their electroluminescence properties, film formation kinetics, and photovoltaic performance are investigated. Both acceptors exhibit strong electroluminescence performance. Moreover, the PBQx-TF:FICC-BO film exhibits enhanced fibril-network morphology. Consequently, the organic photovoltaic (OPV) cells obtain optimized efficiency of 12.0% with decreased nonradiative energy loss of 0.24 eV. image