Exciton-Scissoring Perfluoroarenes Trigger Photomultiplication in Full Color Organic Image Sensors

초록

An unprecedented but useful functionality of perfluoroarenes to enable exciton scissoring in photomultiplication-type organic photodiodes (PM-OPDs) is reported. Perfluoroarenes that are covalently connected to polymer donors via a photochemical reaction enable the demonstration of high external quantum efficiency and B-/G-/R-selective PM-OPDs without the use of conventional acceptor molecules. The operation mechanism of the suggested perfluoroarene-driven PM-OPDs, how covalently bonded polymer donor:perfluoroarene PM-OPDs can perform as effectively as polymer donor:fullerene blend-based PM-OPDs, is investigated. By employing a series of arenes and conducting steady-state/time-resolved photoluminescence and transient absorption spectroscopy analyses, it is found that interfacial band bending between the perfluoroaryl group and polymer donor is responsible for exciton scissoring and subsequent electron trapping, which induces photomultiplication. Owing to the acceptor-free and covalently interconnected photoactive layer in the suggested PM-OPDs, superior operational and thermal stabilities are observed. Finally, finely patterned B-/G-/R-selective PM-OPD arrays that enable the construction of highly sensitive passive matrix-type organic image sensors are demonstrated. Covalent networks consisting of photo-crosslinked polymer donor:perfluoroarene exhibit exciton scissoring and subsequent electron trapping, leading to high EQE photomultiplication-type organic photodiodes together with enhanced stability and fine photo-patternability, without the use of conventional acceptor molecules. This mechanism is enabled by interfacial energy band bending between the perfluoroaryl group and polymer donor, as confirmed by photophysical analyses.image

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