High-efficiency organic light-emitting diodes with fluorescent emitters

• Published in: Nature communications 2014-05, Vol.5 (1), p.4016-4016, Article 4016
• Main Authors: Nakanotani, Hajime, Higuchi, Takahiro, Furukawa, Taro, Masui, Kensuke, Morimoto, Kei, Numata, Masaki, Tanaka, Hiroyuki, Sagara, Yuta, Yasuda, Takuma, Adachi, Chihaya
• Format: Article
• Language: English
• Subjects: 639/301/1019/1020/1091; 639/624/1075; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms5016

Fluorescence-based organic light-emitting diodes have continued to attract interest because of their long operational lifetimes, high colour purity of electroluminescence and potential to be manufactured at low cost in next-generation full-colour display and lighting applications. In fluorescent molecules, however, the exciton production efficiency is limited to 25% due to the deactivation of triplet excitons. Here we report fluorescence-based organic light-emitting diodes that realize external quantum efficiencies as high as 13.4–18% for blue, green, yellow and red emission, indicating that the exciton production efficiency reached nearly 100%. The high performance is enabled by utilization of thermally activated delayed fluorescence molecules as assistant dopants that permit efficient transfer of all electrically generated singlet and triplet excitons from the assistant dopants to the fluorescent emitters. Organic light-emitting diodes employing this exciton harvesting process provide freedom for the selection of emitters from a wide variety of conventional fluorescent molecules. Fluorescent organic light-emitting diodes hold promise for next-generation full-colour displays, but are currently limited by the internal electroluminescence quantum efficiency. Nakanotani et al. break this limit and demonstrate nearly 100% efficiency in a double-dopant system without a rare metal.