Nat. Mater.: Highly Efficient Luminescence from Space-Confined Charge-Transfer Emitters

Title：

Highly Efficient Luminescence from Space-Confined Charge-Transfer Emitters

Authors：

Xun Tang,^#,1 Lin-Song Cui,^#,2,* Hong-Cheng Li,^#,1 Alexander J. Gillett,² Florian Auras,² Yang-Kun Qu,¹ Cheng Zhong,³ Saul T. E. Jones,² Zuo-Quan Jiang,^1,* Richard H. Friend^2,*and Liang-Sheng Liao^1,* 

Institutions：

¹Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, China.

²Cavendish Laboratory, University of Cambridge, Cambridge, UK.

³Department of Chemistry, Hubei Key Laboratory on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan, China.

Abstract：

Charge-transfer (CT) complexes, formed by electron transfer from a donor to an acceptor, play a crucial role in organic semiconductors. Excited-state CT complexes, termed exciplexes, harness both singlet and triplet excitons for light emission, and are thus useful for organic light-emitting diodes (OLEDs). However, present exciplex emitters often suffer from low photoluminescence quantum efficiencies (PLQEs), due to limited control over the relative orientation, electronic coupling and non-radiative recombination channels of the donor and acceptor subunits. Here, we use a rigid linker to control the spacing and relative orientation of the donor and acceptor subunits, as demonstrated with a series of intramolecular exciplex emitters based on 10-phenyl-9,10-dihydroacridine and 2,4,6-triphenyl-1,3,5-triazine. Sky-blue OLEDs employing one of these emitters achieve an external quantum efficiency (EQE) of 27.4% at 67 cd m^-2 with only minor efficiency roll-off (EQE = 24.4%) at a higher luminous intensity of 1,000 cd m^-2. As a control experiment, devices using chemically and structurally related but less rigid emitters reach substantially lower EQEs. These design rules are transferrable to other donor/acceptor combinations, which will allow further tuning of emission colour and other key optoelectronic properties.

IF：

38.663

Link：

https://www.nature.com/articles/s41563-020-0710-z