Advances in Acceptor-Acceptor-Type Conjugated Polymers for NIR Organic Photodetectors
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NIR photodetectors are in high demand for diverse applications. However, limited availability of organic materials detecting NIR is due to the challenge in developing narrow bandgap organic semiconductors. In this study, a novel conjugated polymer (PDPPBTT) with an electron acceptor–electron acceptor (A–A) structure was synthesized using a palladium-catalyzed Stille coupling reaction between diketopyrrolopyrrole (DPP) and benzobisthiadiazole (BBT). The maximum absorbance and absorption onset are 970 nm and 1358 nm, respectively, which are suitable for the detection of visible and NIR light. Using this polymer, we fabricated an NIR organic photodetector, which exhibited detectivity values of 1.1x1011 and 6.4x1010 at wavelengths of 700 nm and 1050 nm, respectively. Additionally, the device demonstrated external quantum efficiency (EQE) values of 67 % and 26 % at those same wavelengths.