Open AccessGenerating Light from Upper Excited Triplet States: A Contribution to the Indirect Singlet Yield of a Polymer OLED, Helping to Exceed the 25% Singlet Exciton Limit
Author(s) -
Jankus Vygintas,
Aydemir Murat,
Dias Fernando B.,
Monkman Andrew P.
Publication year - 2016
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201500221
Subject(s) - singlet state , excited state , oled , exciton , radiative transfer , population , singlet fission , materials science , phosphorescence , yield (engineering) , atomic physics , molecular physics , physics , optoelectronics , fluorescence , condensed matter physics , nanotechnology , quantum mechanics , layer (electronics) , demography , sociology , metallurgy
The mechanisms by which light is generated in an organic light emitting diode have slowly been elucidated over the last ten years. The role of triplet annihilation has demonstrated how the “spin statistical limit” can be surpassed, but it cannot account for all light produced in the most efficient devices. Here, a further mechanism is demonstrated by which upper excited triplet states can also contribute to indirect singlet production and delayed fluorescence. Since in a device the population of these T N states is large, this indirect radiative decay channel can contribute a sizeable fraction of the total emission measured from a device. The role of intra‐ and interchain charge transfer states is critical in underpinning this mechanism.