有机光伏是一种极具潜力的用于驱动室内电子设备的技术。高性能室内有机光伏器件需要中等带隙受体材料来吸收可见光并将其转化为电能。然而，目前典型的高效A-DA’D-A型小分子受体的吸收主要集中在近红外区域，这与室内光源的发射光谱并不匹配。
近日，中国科学院化学研究所李永舫院士和李骁骏副研究员等人在Science China Materials发表研究论文，采用分子协同调控策略合成了两个中等带隙A-DA’D-A型小分子受体，BTOL-Br和DFOL-Br，不仅解决了光谱匹配问题，而且获得了高性能室内光伏受体材料。
本文要点
1) 与BTOL-Br相比，DFOL-Br分子由于其A’单元上的噻二唑单元被两个氟原子取代，因而使其获得了更为蓝移的吸收光谱和显著上移的最低未占据分子轨道能级。材料的这些特性都将有利于DFOL-Br在室内光伏应用中获得更好的表现。2) 将这些小分子受体与聚合物给体PBQx-TCl共混后制备了有机光伏器件，其中基于DFOL-Br分子的活性层表现出更为有序的分子堆积和更合适的相分离尺度。最终，基于DFOL-Br的器件在2600 K LED灯2000 lux的光照强度下表现出26.8%的室内光伏效率，其远高于基于BTOL-Br分子的器件（23.2%）。上述研究结果表明，协同调控是一种有效地调节分子带隙，并制备中等带隙ADA’D-A型小分子受体的策略，该策略或将为可应用于室内光伏的高效小分子受体的设计合成提供借鉴，从而推动室内光伏商业化应用的发展。本文将收录于“2025 Emerging Investigator Issue”。Figure 1. (a) Chemical structures of BTOL-Br and DFOL-Br. (b) ESP diagrams of BTOL-Br and DFOL-Br. (c) Normalized absorption spectra of BTOL-Br and DFOL-Br in solution (chloroform) and in film. (d) Energy level diagram of the donor PBQx-TCl and the SMAs BTOL-Br and DFOL-Br.Figure 2. (a) J-V curves and (b) EQE spectra of the OPVs with PBQx-TCl as donor and BTOL-Br or DFOL-Br as acceptor under the illumination of AM 1.5G, 100 mW cm−2. (c) The dependence of Jph on Veff. (d) Electron and hole mobility of the PBQx-TCl:BTOL-Br and the PBQx-TCl:DFOL-Br blend films. (e) Normalized TPC curve in response to a 100 μs white light pulse. (f) Charge carrier lifetime curve under different Plight obtained from TPV experiments of the BTOL-Br- and the DFOL-Br-based OPVs.Figure 3. (a) Two-dimensional (2D)-GIWAXS patterns and (b) 1D-GIWAXS patterns of the neat BTOL-Br and DFOL-Br films; (c) 2D-GIWAXS patterns and (d) 1D-GIWAXS patterns of the BTOL-Br and DFOL-Br blend films blending with PBQx-TCl. TEM images of the blend films of (e) PBQx-TCl:BTOL-Br and (f) PBQx-TCl:DFOL-Br.Figure 4. J-V characterization of (a) PBQx-TCl:BTOL-Br- and (c) PBQx-TCl:DFOL-Br-based IOPV devices under a 2600 K LED lamp with light intensities of 500, 1000, 1600, and 2000 lux. The photon flux spectrum of 2600 K LED lamp at 500, 1000, 1600, and 2000 lux and the integral current density of (b) BTOL-Br- and (d) DFOL-Br-based IOPVs under the corresponding conditions.Tianwei Zou, Yufei Gong, Xiaojun Li, Guangpei Sun, Ho Ming Ng, Ming Zhang, Han Yu, Zhi-Guo Zhang, Lei Meng, Yongfang Li. Medium bandgap A-DA’D-A type small molecule acceptors prepared by synergetic modification strategy for efficient indoor organic photovoltaic devices. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3135-3
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