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  • 05월 20일 18시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제125회 대한화학회 학술발표회 및 총회 Linear-shaped thermally activated delayed fluorescence emitter using 1,5-naphthyridine as an electron acceptor for efficient light extraction

등록일
2020년 1월 28일 17시 15분 08초
접수번호
0082
발표코드
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발표분야
Organic Chemistry
저자 및
공동저자
Youngnam Lee, Jong-in Hong*
Division of Chemistry, Seoul National University, Korea
Organic light-emitting diodes (OLEDs) have attracted considerable attention as a future display technology. Recently, thermally activated delayed fluorescence (TADF) materials have received a great deal of attention as alternative OLED emitters. TADF emitters require a small singlet-triplet energy gap (ΔEST) and have shown a maximum photoluminescence quantum yield (PLQY) of 100% when triplet (T1) excitons are fully converted to singlet (S1) excitons through reverse intersystem crossing (RISC). For high-efficiency OLEDs, both the internal quantum efficiency (IQE) and external quantum efficiency (EQE) should be considered, where the EQE is related to light out-coupling. Even when the IQE of TADF materials reaches 100%, the theoretical maximum EQE is only 20% for isotropic materials due to limited light out-coupling efficiencies. Therefore, designing emitters that can fully extract electroluminescence through the glass substrate is necessary. These materials tend to be highly linear or planar, the dipoles of which are aligned horizontally when thermally deposited. In this study, we designed a linear-shaped TADF emitter (NyDPAc) by connecting 1,5-naphthylidine as an electron acceptor and dimethylacridine as an electron donor through a phenylene bridge. NyDPAc showed TADF emission due to the orbital separation between the electron donor and acceptor. Furthermore, the rod-like structure of NyDPAc induced horizontal deposition during thermal evaporation, resulting in maximized light out-coupling efficiency. Thus, the NyDPAc-based OLED device showed a high EQE of 20.9% despite a relatively low PLQY (57%). This is the first case of utilizing 1,5-naphthyridine as a linear acceptor for achieving high TADF OLED efficiency.

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