Individual nanostructure optimization in donor and acceptor phases to achieve efficient quaternary organic solar cells

Fullerene derivative (PC₇₁BM) and high crystallinity molecule (DR3TBDTT) are employed into PTB7-Th:FOIC based organic solar cells (OSCs) to cooperate an individual nanostructure optimized quaternary blend. PC₇₁BM functions as molecular adjuster and phase modifier promoting FOIC forming “head-to-head” molecular packing and neutralizing the excessive FOIC crystallites. A multi-scale modified morphology is present thanks to the mixture of FOIC and PC₇₁BM while DR3TBDTT disperses into PTB7-Th matrix to reinforce donor's crystallinity and enhance domain purity. Morphology characterization highlights the importance of individually optimizated nanostructures for donor and acceptor, which contributes to efficient hole and electron transport toward improved carrier mobilities and suppressed non-geminated recombination. Therefore, a power conversion efficiency of 13.51% is realized for a quaternary device which is 16% higher than the binary device (PTB7-Th:FOIC). This work demonstrates that utilizing quaternary strategy for simultaneous optimization of donor and acceptor phases is a feasible way to realize high efficient OSCs.