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Ultranarrow-bandgap small-molecule acceptor enables sensitive SWIR detection and dynamic upconversion imaging.

Yongjie ChenYingqi ZhengJing WangXuan ZhaoGuanhao LiuYi LinYubo YangLixiang WangZheng TangYing WangYanjun FangWenkai ZhangXiao-Zhang Zhu
Published in: Science advances (2024)
Short-wavelength infrared (SWIR) light detection plays a key role in modern technologies. Emerging solution-processed organic semiconductors are promising for cost-effective, flexible, and large-area SWIR organic photodiodes (OPDs). However, the spectral responsivity ( R ) and specific detectivity ( D *) of SWIR OPDs are restricted by insufficient exciton dissociation and high noise current. In this work, we synthesized an SWIR small molecule with a spectral coverage of 0.3 to 1.3 micrometers peaking at 1100 nanometers. The photodiode, with optimized exciton dissociation, charge injection, and SWIR transmittance, achieves a record high R of 0.53 ampere per watt and D * of 1.71 × 10 13 Jones at 1110 nanometers under zero bias. The D * at 1 to 1.2 micrometers surpasses that of the uncooled commercial InGaAs photodiode. Furthermore, large-area semitransparent all-organic upconversion devices integrating the SWIR photodiode realized static and dynamic SWIR-to-visible imaging, along with excellent upconversion efficiency and spatial resolution. This work provides alternative insights for developing sensitive organic SWIR detection.
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