Triplet harvesting with 100% efficiency by way of thermally activated delayed fluorescence in charge transfer OLED emitters

Triplet harvesting with 100% efficiency by way of thermally activated delayed fluorescence in charge transfer OLED emitters

Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bibliographische Detailangaben
Veröffentlicht in:Advanced materials (Deerfield Beach, Fla.). - 1998. - 25(2013), 27 vom: 19. Juli, Seite 3707-14
1. Verfasser: Dias, Fernando B (VerfasserIn)
Weitere Verfasser: Bourdakos, Konstantinos N, Jankus, Vygintas, Moss, Kathryn C, Kamtekar, Kiran T, Bhalla, Vandana, Santos, José, Bryce, Martin R, Monkman, Andrew P
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2013
Zugriff auf das übergeordnete Werk:Advanced materials (Deerfield Beach, Fla.)
Schlagworte:Journal Article conjugated materials delayed fluorescence organic light-emitting diodes organic semiconductors
Beschreibung
Zusammenfassung:Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Organic light-emitting diodes (OLEDs) have their performance limited by the number of emissive singlet states created upon charge recombination (25%). Recently, a novel strategy has been proposed, based on thermally activated up-conversion of triplet to singlet states, yielding delayed fluorescence (TADF), which greatly enhances electroluminescence. The energy barrier for this reverse intersystem crossing mechanism is proportional to the exchange energy (ΔEST ) between the singlet and triplet states; therefore, materials with intramolecular charge transfer (ICT) states, where it is known that the exchange energy is small, are perfect candidates. However, here it is shown that triplet states can be harvested with 100% efficiency via TADF, even in materials with ΔEST of more than 20 kT (where k is the Boltzmann constant and T is the temperature) at room temperature. The key role played by lone pair electrons in achieving this high efficiency in a series of ICT molecules is elucidated. The results show the complex photophysics of efficient TADF materials and give clear guidelines for designing new emitters
Beschreibung:Date Completed 07.04.2014
Date Revised 30.09.2020
published: Print-Electronic
Citation Status PubMed-not-MEDLINE
ISSN:1521-4095
DOI:10.1002/adma.201300753