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

Chen, Yongjie; Zheng, Yingqi; Wang, Jing; Zhao, Xuan; Liu, Guanhao; Lin, Yi; Yang, Yubo; Wang, Lixiang et al. · Sci Adv · 2024

basic_science · Level V

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Abstract

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 (<i>R</i>) and specific detectivity (<i>D</i>*) 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 <i>R</i> of 0.53 ampere per watt and <i>D</i>* of 1.71 × 10<sup>13</sup> Jones at 1110 nanometers under zero bias. The <i>D</i>* 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.