近日，东莞理工大学的房学谦与深圳大学的曾昱嘉等人合作并取得一项新进展。他们利用极化子辅助有机整数电荷转移杂化，解锁高性能近红外光电的探测。相关研究成果已于2024年12月9日在国际知名学术期刊《光：科学与应用》上发表。

即使在商用无机红外（IR）光探测器（PD）中，室温下的飞瓦级灵敏度也依然是备受追捧的特性。虽然有机IR光探测器有望在即将到来的第四代工业时代成为关键的传感器技术，但其性能仍落后于无机光探测器。这种差异主要源于有机IR材料的外部量子效率（EQE）较低，这是由于材料内部激子解离不足（激子结合能高）所致，而窄带隙中显著的非辐射复合效应进一步加剧了这一问题。

该研究团队揭示了一种高性能有机近红外（NIR）光探测器（PD），该探测器通过聚 (2,5-双 (3-十四烷基噻吩-2-基)噻吩并 [3,2-b]噻吩) （C-14PBTTT）给体（D），与四氟四氰基醌二甲烷（TCNQF4）受体（A）分子之间的整数电荷转移实现，展现出了高达2.5微米的强低能子带隙吸收。

研究人员观察到，特别是在这些自由基和中性D-A混合分子中，极化子的激发使得束缚电荷能够克服其与反离子的库仑吸引力，从而与弗伦克尔激子相比，实现了更高的外部量子效率（EQE，在极化子吸收区域）。

因此，该研究的器件在室温下、波长为1.0微米时，实现了高约107%的EQE、0.12 fW Hz^-1/2的飞瓦级灵敏度（NEP）以及81毫秒的响应时间。

研究人员创新性地利用极化子，凸显了它们作为高性能有机IR光探测器中弗伦克尔激子替代品的潜力。

附：英文原文

Title: Unlocking high-performance near-infrared photodetection: polaron-assisted organic integer charge transfer hybrids

Author: Iqbal, Muhammad Ahsan, Fang, Xueqian, Abbas, Yasir, Weng, Xiaoliang, He, Tingchao, Zeng, Yu-Jia

Issue&Volume: 2024-12-09

Abstract: Room temperature femtowatt sensitivity remains a sought-after attribute, even among commercial inorganic infrared (IR) photodetectors (PDs). While organic IR PDs are poised to emerge as a pivotal sensor technology in the forthcoming Fourth-Generation Industrial Era, their performance lags behind that of their inorganic counterparts. This discrepancy primarily stems from poor external quantum efficiencies (EQE), driven by inadequate exciton dissociation (high exciton binding energy) within organic IR materials, exacerbated by pronounced non-radiative recombination at narrow bandgaps. Here, we unveil a high-performance organic Near-IR (NIR) PD via integer charge transfer between Poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (C-14PBTTT) donor (D) and Tetrafluorotetracyanoquinodimethane (TCNQF4) acceptor (A) molecules, showcasing strong low-energy subgap absorptions up to 2.5μm. We observe that specifically, polaron excitation in these radical and neutral D-A blended molecules enables bound charges to exceed the Coulombic attraction to their counterions, leading to an elevated EQE (polaron absorption region) compared to Frenkel excitons. As a result, our devices achieve a high EQE of ～107%, femtowatt sensitivity (NEP) of ~0.12 fW Hz^-1/2 along a response time of ~81ms, at room temperature for a wavelength of 1.0μm. Our innovative utilization of polarons highlights their potential as alternatives to Frenkel excitons in high-performance organic IR PDs.

DOI: 10.1038/s41377-024-01695-9

Source: https://www.nature.com/articles/s41377-024-01695-9