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High Performance Shortwave Infrared Organic Photodetectors Adopting Thiadiazole Quinoxaline-based Copolymers

Advanced Optical Materials

Detecting invisible wavelengths such as near infrared and shortwave infrared (SWIR) is emerging for the wide practical applications of biometrics, surveillance, machine vision, etc, in which organic molecules have gained growing interest as the potential sensing materials. In this study, we present newly synthesized donor-acceptor type copolymers consisting of [1,2,5]thiadiazolo[3,4-g]quinoxaline core unit with the phenyl pendant group as an acceptor and thiophene unit as a donor for achieving high efficiency organic SWIR photodetectors. The optimized device by further variation of the alkoxy chain lengths in the core unit exhibits high EQE of 19.5 ? 21.7% at 1200 nm under the low reverse bias of -1 V and the consequently high detectivity up to 2.96 × 1010 Jones, which is one of the highest values among the organic SWIR detectors (λ > 1 μm). We further offer the possible origin of the molecular structure dependent device performance in terms of the analysis of the molecular stacking, the morphological change, and the charge transporting property.

Adv. Optical Mater. 2022, 2200747