Design of All-Small-Molecule Organic Solar Cells Approaching 14% Efficiency via Isometric Terminal Alkyl Chain Engineering

Morphology is crucial to determining the photovoltaic performance of organic solar cells (OSCs). However, manipulating morphology involving only small-molecule donors and acceptors extremely challenging. Herein, a simple terminal alkyl chain engineering process introduced fine-tune towards high-performance all-small-molecule (ASM) OSCs. We successfully chose chlorinated two-dimension benzo[1,2-b:4,5-b?]dithiophene (BDT) central unit two isomeric cyanoacetate as end-capped moieties conveniently synthesize donors, namely, BT-RO-Cl BT-REH-Cl, each bearing linear n-octyl (O) another branched 2-ethylhexyl (EH) chain. The provided with 13.35% efficiency BT-REH-Cl 13.90% ASM OSCs, both Y6 electron acceptor. successful resulted from uniform phase separation favorable combination face-on edge-on molecular stacking blended acceptors, which formed fluent 3D transport channel thus delivered high balanced carrier mobilities. These findings demonstrate that can finely control provides an alternative for optimal design materials