Realizing 20% External Quantum Efficiency in Electroluminescence with Efficient Thermally Activated Delayed Fluorescence from an Exciplex

Abstract

The investigation of non-doped exciplex blends of 2,4,6-Tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T), working as the one-electron acceptor molecule, with different electron donors is reported. The emissions of these exciplexes span from the blue to orange-red regions, showing clear contribution from thermally activated delayed fluorescence (TADF) and delayed fluorescence originated from non-geminate recombination of charge carriers created by the dissociation of optically generated exciplexes. We focus our

Identifying the Factors That Lead to PLQY Enhancement in Diluted TADF Exciplexes Based on Carbazole Donors

“…The absorption spectra of the individual components were reported previously and confirm that only the donors have appreciable absorption at 330, 337, and 355nm used for excitation in subsequent optical experiments. 6,12,14,15 All three exciplexes exhibit a blue shift of their PL with increasing dilution (Figure 2), consistent with our recent discovery of the dilution effect in the TSBPA:PO-T2T exciplex system. 6 This blue shift is rationalised in terms of a decreased coulombic energy term for the exciplex as the electron-hole separation of the charge transfer (CT) excited state increases.…”

Revealing the Cooperative Relationship between Spin, Energy, and Polarization Parameters toward Developing High‐Efficiency Exciplex Light‐Emitting Diodes

“…The advantages and versatile applications of exciplex systems for giving high‐efficiency OLEDs have been highlighted recently . More significantly, OLEDs with exciplex‐forming systems as emitting layer have been reported to achieve EQE higher than 19%, manifesting their bright and promising prospects in OLED technology based on physically mixing donor and acceptor molecules. The highest EQE of 21.7% has been realized in a 4,4′‐cyclohexylidenebis[ N , N ‐bis(4‐methylphenyl)benzenamine] (TAPC):di‐[4‐( N , N ‐ditoly amino)‐phenyl]cyclohexane (PIM‐TRZ) exciplex OLED very recently .…”

Tricomponent Exciplex Emitter Realizing over 20% External Quantum Efficiency in Organic Light‐Emitting Diode with Multiple Reverse Intersystem Crossing Channels

“…Therefore, the evidently improved Φ PL of DBT-SADF:PO-T2T:CDBP is actually ascribed to the better upconversion of triplet excitons with three RISC channels and prove the feasibility of our strategy to improve the exciton utilization of exciplex emitters. Moreover, to the best of our knowledge, this is the first report with an EQE over 20% for the OLEDs based on exciplex emitters at room temperature (Figure 4; Table S2, Supporting Information), [1,2,[4][5][6][7][8][9][10][11][12][13][14][17][18][19][20][21]30,31,[46][47][48] thus our novel strategy of tricomponent exciplexes will provide a valuable approach for further development of exciplex emitters. As the mixing ratios of exciplexes would change their charge balance and affect the device performance, [13,14] the carrier transporting properties of four exciplexes were carefully investigated.…”

“…The lower-energy exciplex could be beneficial due to the energy transfer between two exciplexes. [1,2,[4][5][6][7][8][9][10][11][12][13][14][17][18][19][20][21]30,31,[46][47][48] The outstanding performance of the DBT-SADF:PO-T2T:CDBP-based OLEDs not only demonstrates that introducing multiple RISC channels can effectively improve the exciton utilization of exciplex emitters, but also proves the superiority of our novel tricomponent exciplex strategy for further development of exciplex emitters. According to our novel strategy, two tricomponent exciplex emitters, 13AB ((1,3-bis(9,9dimethylacridin)) benzene):PO-T2T ((1,3,5-triazine-2,4,6-triyl) tris(benzene-3,1-diyl) tris(diphenylphosphine oxide)):CDBP (4,4′-bis(9-carbazolyl)-2,2′-dimethylbiphenyl) and DBT-SADF Energy transfer diagrams of the conventional bicomponent TADF exciplexes, TADF-assistant bicomponent TADF exciplexes, and novel tricomponent TADF exciplexes (blue: conventional constituent material, orange: single-molecule TADF emitter).…”