Long-range exciton diffusion in non-fullerene acceptors and coarse bulk heterojunctions enable highly efficient organic photovoltaics†
We investigated singlet exciton diffusion in three ITIC derivatives used as electron acceptors in organic photovoltaics (OPVs) by time-resolved photoluminescence volume quenching and exciton–exciton annihilation. The exciton diffusion coefficient was found to be in the range of 0.003–0.007 cm2 s−1 which leads to a three-dimensional exciton diffusion length of up to 31 nm. We fabricated solar cells using bulk heterojunctions of these acceptors with the electron donor PTB7-Th which showed ∼7% efficiency and large scale phase separation. Our results show that long range exciton diffusion and large domains offer significant advantages for OPVs.
- This article is part of the themed collections: Recent Open Access Articles and Journal of Materials Chemistry A Emerging Investigators