Towards high-efficiency non-fullerene organic solar cells: Matching small molecule/polymer donor/acceptor

• Four small molecule/polymer donors/acceptors were used to fabricate non-fullerene organic solar cells.
• The effects of donor/acceptor combinations on morphology, charge transport and device performance were investigated.
• Polymer/polymer and small molecule/small molecule pairs exhibited much higher PCEs than polymer/small molecule pairs.

Two low band-gap donors, small molecule p-DTS(FBTTh2)2 (SD) and polymer PBDTTT-C-T (PD), and two perylene diimide acceptors, small molecule PDI-2DTT (SA) and polymer PPDIDTT (PA), were used to fabricate non-fullerene organic solar cells. The effects of four donor/acceptor combinations, PD/PA, PD/SA, SD/SA and SD/PA, on the morphology, charge transfer, charge transport and photovoltaic performance were investigated. Power conversion efficiencies (PCEs) of PD/PA, PD/SA, SD/SA and SD/PA were 3.04%, 0.28%, 2.52% and 0.29%, respectively. The PD/PA blend and SD/SA blend exhibited relatively uniform and continuous morphology, efficient photoinduced charge transfer, high mobility and balanced charge transport relative to PD/SA and SD/PA blends, leading to much higher PCEs.

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