Issue 34, 2024

Tailoring structural rigidity utilizing a lock/unlock donor strategy for highly efficient solution processed blue and green HLCT OLEDs

Abstract

Highly efficient solution-processed HLCT OLEDs based on aromatic carbonyls are rarely reported, especially blue ones. In this pursuit, based on a twisted acceptor core, we designed and synthesized two unsymmetrical keto-carbonitrile emitters, namely, KCPhCz and KCPhDPA, utilizing a locked (carbazole) and unlocked (diphenylamine) donor strategy exhibiting color tunability. Additionally, we found that the insertion of a π-linker between the donor and acceptor converted an inefficient TADF emitter (KCCz, previously reported) into an efficient blue HLCT emitter (KCPhCz). We found this efficiency enhancement based on a weak carbazole donor was due to HLCT characteristics. KCPhCz and KCPhDPA-based molecules emitted in the blue and green regions respectively. Non-doped devices based on KCPhCz and KCPhDPA exhibited EQEs of 5.7 and 7.4%, respectively. The best performance was demonstrated by 7.5 wt% doped devices from both emitters. The KCPhDPA-based device showed a PEmax of 39.2 lm W−1, a CEmax of 49.8 cd A−1, and an EQEmax of 15.3% at a brightness of 100 cd m−2 with CIE of (0.34, 0.58) and EL λmax at 532 nm. In contrast, the KCPhCz-based optimized device showed a PEmax of 22.7 lm W−1, a CEmax of 32.5 cd A−1, and an EQEmax of 10.8% at a brightness of 100 cd m−2 in the blue region with CIE of (0.18, 0.19) where EL showed λmax at 480 nm.

Graphical abstract: Tailoring structural rigidity utilizing a lock/unlock donor strategy for highly efficient solution processed blue and green HLCT OLEDs

Supplementary files

Article information

Article type
Paper
Submitted
30 Jan 2024
Accepted
17 Jul 2024
First published
17 Jul 2024

J. Mater. Chem. C, 2024,12, 13585-13595

Tailoring structural rigidity utilizing a lock/unlock donor strategy for highly efficient solution processed blue and green HLCT OLEDs

M. I. Alam, M. R. Nagar, D. Barman, P. K. Iyer, J. Jou and S. Vaidyanathan, J. Mater. Chem. C, 2024, 12, 13585 DOI: 10.1039/D4TC00417E

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