Interface Engineering in Perylene Diimide-Based Organic Photovoltaics with Enhanced Photovoltage
Aiswarya Abhisek Mohapatra, Manasi Pranav, Suraj Yadav, Chandrasekhar Gangadharappa, Jiaying Wu, Chiara Labanti, Jakob Wolansky, Johannes Benduhn, Ji‐Seon Kim, James R. Durrant, Satish Patil
Abstract
The introduction of nonfullerene acceptors (NFA) facilitated the realization of high-efficiency organic solar cells (OSCs); however, OSCs suffer from relatively large losses in open-circuit voltage ( V OC ) as compared to inorganic or perovskite solar cells. Further enhancement in power conversion efficiency requires an increase in V OC . In this work, we take advantage of the high dipole moment of twisted perylene-diimide (TPDI) as a nonfullerene acceptor (NFA) to enhance the V OC of OSCs. In multiple bulk heterojunction solar cells incorporating TPDI with three polymer donors (PTB7-Th, PM6 and PBDB-T), we observed a V OC enhancement by modifying the cathode with a polyethylenimine (PEIE) interlayer. We show that the dipolar interaction between the TPDI NFA and PEIE─enhanced by the general tendency of TPDI to form J-aggregates─plays a crucial role in reducing nonradiative voltage losses under a constant radiative limit of V OC . This is aided by comparative studies with PM6:Y6 bulk heterojunction solar cells. We hypothesize that incorporating NFAs with significant dipole moments is a feasible approach to improving the V OC of OSCs.