Organic molecules have been regarded as ideal candidates for near-infrared (NIR) optoelectronic active materials due to their customizability and ease of large-scale production. However, constrained by the intricate molecular design and severe energy gap law, the realization of optoelectronic devices in the second near-infrared (NIR (II)) region with required narrow band gaps presents more challenges. Herein, we have originally proposed a cocrystal strategy that utilizes intermolecular charge–transfer interaction to drive the redshift of absorption and emission spectra of a series BF_XTQ (X = 0, 1, 2, 4) cocrystals, resulting in the spectra located at NIR (II) window and reducing the optical bandgap to ∼0.98 eV. Significantly, these BF_XTQ-based optoelectronic devices can exhibit dual-mode optoelectronic characteristics. An investigation of a series of BF_XTQ-based photodetectors exhibits detectivity (D*) surpassing 10¹³ Jones at 375 to 1064 nm with a maximum of 1.76 × 10¹⁴ Jones at 1064 nm. Moreover, the radiative transition of CT excitons within the cocrystals triggers NIR emission over 1000 nm with a photoluminescence quantum yield (PLQY) of ∼4.6% as well as optical waveguide behavior with a low optical-loss coefficient of 0.0097 dB/μm at 950 nm. These results promote the advancement of an emerging cocrystal approach in micro/nanoscale NIR multifunctional optoelectronics.

中文翻译：

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用于近红外 (II) 窗口双模光电器件的可定制有机电荷转移共晶

有机分子由于其可定制性和易于大规模生产而被认为是近红外（NIR）光电活性材料的理想候选者。然而，受复杂的分子设计和严格的能隙定律的限制，在第二近红外（NIR（II））区域实现窄带隙光电器件面临更多挑战。在此，我们最初提出了一种共晶策略，利用分子间电荷转移相互作用来驱动一系列 BF _X TQ ( X = 0, 1, 2, 4) 共晶的吸收和发射光谱的红移，导致光谱位于NIR (II) 窗口并将光学带隙减小至 ∼0.98 eV。值得注意的是，这些基于 BF _X TQ 的光电器件可以表现出双模光电特性。对一系列基于 BF _X TQ 的光电探测器的研究表明，在 375 至 1064 nm 处的探测率 ( D *) 超过 10 ¹³琼斯，在 1064 nm 处的最大值为 1.76 × 10 ¹⁴琼斯。此外，共晶内 CT 激子的辐射跃迁触发了超过 1000 nm 的近红外发射，光致发光量子产率 (PLQY) 约为 4.6%，并且光波导行为在 950 nm 处具有 0.0097 dB/μm 的低光损耗系数。这些结果促进了微/纳米级近红外多功能光电子学中新兴共晶方法的进步。