Singlet and triplet to doublet energy transfer: improving organic light-emitting diodes with radicals.


Type
Article
Change log
Authors
Gillett, Alexander J  ORCID logo  https://orcid.org/0000-0001-7572-7333
Gu, Qinying 
Ding, Junshuai 
Chen, Zhangwu 
Abstract

Organic light-emitting diodes (OLEDs) must be engineered to circumvent the efficiency limit imposed by the 3:1 ratio of triplet to singlet exciton formation following electron-hole capture. Here we show the spin nature of luminescent radicals such as TTM-3PCz allows direct energy harvesting from both singlet and triplet excitons through energy transfer, with subsequent rapid and efficient light emission from the doublet excitons. This is demonstrated with a model Thermally-Activated Delayed Fluorescence (TADF) organic semiconductor, 4CzIPN, where reverse intersystem crossing from triplets is characteristically slow (50% emission by 1 µs). The radical:TADF combination shows much faster emission via the doublet channel (80% emission by 100 ns) than the comparable TADF-only system, and sustains higher electroluminescent efficiency with increasing current density than a radical-only device. By unlocking energy transfer channels between singlet, triplet and doublet excitons, further technology opportunities are enabled for optoelectronics using organic radicals.

Description
Keywords
40 Engineering, 34 Chemical Sciences, 3406 Physical Chemistry, 7 Affordable and Clean Energy
Journal Title
Nat Commun
Conference Name
Journal ISSN
2041-1723
2041-1723
Volume Title
13
Publisher
Springer Science and Business Media LLC
Sponsorship
Engineering and Physical Sciences Research Council (EP/M005143/1)
Engineering and Physical Sciences Research Council (EP/M01083X/1)
European Research Council (670405)
European Commission Horizon 2020 (H2020) ERC (101020167)