Eliminating the Reverse ISC Bottleneck of TADF Through Excited State Engineering and Environment‐Tuning Toward State Resonance Leading to Mono‐Exponential Sub‐µs Decay. High OLED External Quantum Efficiency Confirms Efficient Exciton Harvesting

URN zum Zitieren dieses Dokuments:

urn:nbn:de:bvb:355-epub-528250 Copy

DOI zum Zitieren dieses Dokuments:

10.5283/epub.52825 Copy

Yersin, Hartmut ; Czerwieniec, Rafal ; Mataranga‐Popa, Larisa ; Mewes, Jan‐Michael ; Cheng, Gang ; Che, Chi‐Ming ; Saigo, Masaki ; Kimura, Shuji ; Miyata, Kiyoshi ; Onda, Ken

Lizenz: Creative Commons Namensnennung-NichtKommerziell-KeineBearbeitung 4.0 International PDF - Veröffentlichte Version (2MB)

Veröffentlichungsdatum dieses Volltextes: 30 Aug 2022 05:59

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Alternative Links zum Volltext:DOIVerlag

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Diese Publikation ist Teil des DEAL-Vertrags mit Wiley.

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Details

Dokumentenart:	Artikel
Open Access Art:	DEAL (Wiley)
Titel eines Journals oder einer Zeitschrift:	Advanced Functional Materials
Verlag:	WILEY-V C H VERLAG GMBH
Ort der Veröffentlichung:	WEINHEIM
Band:	32
Nummer des Zeitschriftenheftes oder des Kapitels:	34
Seitenbereich:	S. 2201772
Datum:	15 Juni 2022
Institutionen:	Chemie und Pharmazie > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Molecular Spectroscopy and Photochemistry) > Prof. Dr. Hartmut Yersin
Identifikationsnummer:	Wert Typ 10.1002/adfm.202201772 DOI
Stichwörter / Keywords:	ACTIVATED DELAYED FLUORESCENCE; PHOTOPHYSICAL PROPERTIES; ELECTRONIC STATES; PT(II) COMPOUNDS; DESIGN STRATEGY; HIGH-RESOLUTION; CHARGE-TRANSFER; SINGLET; CU(I); BENZOPHENONE; OLEDs; state tuning; ultra-fast reverse intersystem crossing; ultra-small singlet-triplet gap; thermally activated delayed fluorescence
Dewey-Dezimal-Klassifikation:	500 Naturwissenschaften und Mathematik > 540 Chemie
Status:	Veröffentlicht
Begutachtet:	Ja, diese Version wurde begutachtet
An der Universität Regensburg entstanden:	Zum Teil
Dokumenten-ID:	52825

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Zusammenfassung

The electronic structure and photophysics of the recently designed organic direct singlet harvesting (DSH) molecule are explored, in which donor (D) and acceptor (A) are held at distance by two bridges. One of the bridges is functionalized with fluorene. This structure leads to an ultrasmall singlet-triplet energy gap of increment E (S-1-T-1) approximate to 10 cm(-1) (approximate to 1 meV) ...

Zusammenfassung

The electronic structure and photophysics of the recently designed organic direct singlet harvesting (DSH) molecule are explored, in which donor (D) and acceptor (A) are held at distance by two bridges. One of the bridges is functionalized with fluorene. This structure leads to an ultrasmall singlet-triplet energy gap of increment E (S-1-T-1) approximate to 10 cm(-1) (approximate to 1 meV) between the charge transfer states (CT)-C-1,3 and shows an energetically close-lying (3)pi pi* state localized on fluorene. Dielectric constant variation of the environment leads to state crossing of (3)pi pi* and (CT)-C-1,3 near epsilon = 2.38 (toluene), as confirmed through time-dependent density functional theory (DFT) and state-specific DFT/polarizable continuum model excited-state calculations. Transient absorption (TA) and time-resolved luminescence in the femtosecond to microsecond regimes show rates of intersystem crossing (ISC) and reverse ISC (rISC) of >10(9) s(-1). Thus, a strictly mono-exponential short-lived photo-luminescence decay (431 ns) is observed, revealing that rISC is no longer the bottleneck responsible for long thermally activated delayed fluorescence. Ultrafast TA displays a time constant of approximate to 700 fs, representing the relaxation time of DSH and its solvent environment to the relaxed (CT)-C-1 state with a molecular dipole moment of approximate to 40 D. Importantly, OLED devices, emitting sky-blue light and showing high external quantum efficiency of 19%, confirm that singlet and triplet excitons are harvested efficiently.

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