Ternary strategy enabling high-efficiency rigid and flexible organic solar cells with reduced non-radiative voltage loss

The ternary strategy has been identified as a feasible and effective way to obtain high-efficiency organic solar cells (OSCs). However, for most ternary OSCs, the voltage loss (V-loss) lies between those of the two binary devices, which inevitably limits the further efficiency improvements. Herein, a non-fullerene acceptor ZY-4Cl, possessing complementary absorption spectra and forming a cascade LUMO energy level alignment with the PM6:BTP-eC9 blend, was introduced as a third component to fabricate ternary OSCs. Compared to the binary blends, the ternary system exhibits reduced density of trap states, improved molecular ordering, and suppressed non-radiative recombination, and thereby yields an obviously lower V-loss than either of the binary OSCs. As a result, high efficiencies of 18.69% (certified as 18.2%) and 16.07% are obtained for the rigid and flexible OSCs, respectively. This work highlights the importance of suppressing non-radiative recombination in OSCs by using a ternary strategy and expands an effective avenue for the realization of efficient wearable electronics as novel photovoltaic power sources.

Automated summary

This study demonstrates the successful fabrication of efficient ternary organic solar cells by introducing ZY-4Cl as a third component. The ternary system exhibits reduced voltage loss, improved molecular ordering, and suppressed non-radiative recombination, leading to higher efficiencies compared to binary blends.