Department of Chemistry and Centre for Plastic Electronics and ‡Department of Physics and Centre for Plastic Electronics, Imperial College London , London SW7 2AZ, United Kingdom.
J Am Chem Soc. 2015 Jan 21;137(2):898-904. doi: 10.1021/ja5110602. Epub 2015 Jan 12.
A novel small molecule, FBR, bearing 3-ethylrhodanine flanking groups was synthesized as a nonfullerene electron acceptor for solution-processed bulk heterojunction organic photovoltaics (OPV). A straightforward synthesis route was employed, offering the potential for large scale preparation of this material. Inverted OPV devices employing poly(3-hexylthiophene) (P3HT) as the donor polymer and FBR as the acceptor gave power conversion efficiencies (PCE) up to 4.1%. Transient and steady state optical spectroscopies indicated efficient, ultrafast charge generation and efficient photocurrent generation from both donor and acceptor. Ultrafast transient absorption spectroscopy was used to investigate polaron generation efficiency as well as recombination dynamics. It was determined that the P3HT:FBR blend is highly intermixed, leading to increased charge generation relative to comparative devices with P3HT:PC60BM, but also faster recombination due to a nonideal morphology in which, in contrast to P3HT:PC60BM devices, the acceptor does not aggregate enough to create appropriate percolation pathways that prevent fast nongeminate recombination. Despite this nonoptimal morphology the P3HT:FBR devices exhibit better performance than P3HT:PC60BM devices, used as control, demonstrating that this acceptor shows great promise for further optimization.
一种新型小分子 FBR 带有 3-乙基绕丹宁侧翼基团，被合成作为一种非富勒烯电子受体，用于溶液处理的体异质结有机光伏（OPV）。采用了一种直接的合成路线，为这种材料的大规模制备提供了可能。采用聚（3-己基噻吩）（P3HT）作为给体聚合物和 FBR 作为受体的倒置 OPV 器件的功率转换效率（PCE）高达 4.1%。瞬态和稳态光学光谱表明，从供体和受体都能有效地进行超快电荷生成和有效的光电流生成。超快瞬态吸收光谱用于研究极化子生成效率和复合动力学。结果表明，P3HT:FBR 共混物高度混合，导致与具有 P3HT:PC60BM 的比较器件相比，电荷生成增加，但由于非理想形态，复合也更快，其中，与 P3HT:PC60BM 器件相反，受体没有聚集到足以形成适当的渗流途径，防止快速非辐射复合。尽管这种非理想形态，P3HT:FBR 器件的性能优于用作对照的 P3HT:PC60BM 器件，这表明这种受体具有进一步优化的巨大潜力。
