High performance organic solar cell enabled by manipulating the exciton dissociation and charge transfer via dielectric engineering

As core processes determining the power conversion efficiency (PCE) of organic solar cells (OSCs), exciton dissociation and charge transfer are fundamentally restricted by the low intrinsic dielectric constant of organic semiconductors. Herein, two dielectric regulators (Drs) named Dr-1 and Dr-2 are judiciously designed with different molecular dipole moments to conduct research on dielectric engineering. The incorporation of S···F noncovalent conformational locks (NoCLs) endows Dr-2 with an extended π-conjugated backbone, improved molecular polarizability, reinforced charge delocalization and a larger dipole moment than Dr-1. Thus, Dr-2-modified OSCs based on the D18:L8-BO system achieve a PCE of 20.85%, surpassing the 20.13% of Dr-1-treated counterparts. Enhanced efficiencies across diverse donor-acceptor systems confirm the universal applicability of this strategy. Furthermore, 300 nm-thick OSCs incorporated with Dr-2 deliver a record-high PCE of 19.56%. This work provides a strategy for designing high-performance dielectric regulators via tuning molecular dipole moment and planarity simultaneously, thereby achieving high-efficiency OSCs.