Zhang Yingze, Yu Yingjian, Liu Xinyu, Miao Junhui, Han Yanchun, Liu Jun, Wang Lixiang
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, P. R. China.
Adv Mater. 2023 May;35(20):e2211714. doi: 10.1002/adma.202211714. Epub 2023 Mar 30.
Most of all-fused-ring π-conjugated molecules have wide or medium bandgap and show photo response in the visible range. In this work, an all-fused-ring n-type molecule, which exhibits an ultrasmall optical bandgap of 1.22 eV and strong near-infrared (NIR) absorption with an onset absorption wavelength of 1013 nm is reported. The molecule consists of 14 aromatic rings and has electron donor-acceptor characteristics. It exhibits excellent n-type properties with low-lying HOMO/LUMO energy levels of -5.48 eV/-3.95 eV and high electron mobility of 7.0 × 10 cm V s . Most importantly, its thin film exhibits a low trap density of 5.55 × 10 cm because of the fixed molecular conformation and consequently low conformation disorder. As a result, organic photodetector (OPD) based on the compound exhibits a remarkably low dark current density (J ) of 2.01 × 10 A cm at 0 V. The device shows a shot-noise-limited specific detectivity (D *) of exceeding 10 Jones at 400-1000 nm wavelength region with a peak specific detectivity of 4.65 × 10 Jones at 880 nm. This performance is among the best reported for self-powered NIR OPDs.
大多数全稠环π共轭分子具有宽带隙或中带隙，并在可见光范围内表现出光响应。在这项工作中，报道了一种全稠环n型分子，其具有1.22 eV的超小光学带隙和1013 nm的起始吸收波长的强近红外（NIR）吸收。该分子由14个芳环组成，具有电子供体-受体特性。它具有优异的n型性能，HOMO/LUMO能级较低，为-5.48 eV/-3.95 eV，电子迁移率高达7.0×10 cm V s。最重要的是，由于分子构象固定且构象无序度低，其薄膜的陷阱密度低至5.55×10 cm。因此，基于该化合物的有机光电探测器（OPD）在0 V时的暗电流密度（J）极低，为2.01×10 A cm。该器件在400-1000 nm波长区域的散粒噪声限制比探测率（D*）超过10 Jones，在880 nm处的峰值比探测率为4.65×10 Jones。这一性能是自供电近红外OPD中报道的最佳性能之一。
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