Morphology and charge recombination effects on the performance of nearinfrared photodetectors based on conjugated polymers
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초록
내용
Near-infrared (NIR) photodetectors were fabricated through a solution process using two different conjugated polymers (CPs) that share a similar backbone consisting of a DPP moiety. However, their detection capabilities were significantly different depending on the applied linkers, namely thiophene for PDPP-T and fluorinated thiophene for PDPP-FBT. First, we revealed that employing an additive was beneficial to optimize film morphology for both CPs, suppressing dark current and enhancing detectivity. Additionally, it was clearly demonstrated via transient photovoltage measurements that the charge recombination time was lengthened by introducing a highly electronegative fluorine atom into the conjugated skeleton, which implies an increase in the probability of charge extraction. Conclusively, both film morphology and surface dipoles of CPs are equally important to achieve high detectivity and responsivity in organic NIR photodetectors.