Highly fluorescent room temperature liquid crystalline S-annulated swallow tail perylene bisimide exhibiting enhanced electroluminescence (EQE > 11%)

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2024-05, Vol.12 (19), p.6893-694
• Main Authors: Behera, Paresh Kumar, Lenka, Sushanta, Chen, Feng-Rong, Gautam, Prakalp, Siddiqui, Iram, Rao, D. S. Shankar, Jou, Jwo-Huei, Achalkumar, Ammathnadu Sudhakar
• Format: Article
• Language: English
• Subjects: Charge transfer; Emitters; Energy transfer; Fluorescence; Liquid crystals; Optical properties; Organic light emitting diodes; Photoluminescence; Quantum efficiency; Room temperature; Self-assembly
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d3tc04407f

The demand for synthesizing highly luminescent compounds has emerged as a pivotal necessity in order to facilitate cost-effective and metal-free production of organic light-emitting diodes (OLEDs) on a commercial scale. This investigation introduces a readily soluble, electron deficient S-annulated perylene bisimide ( PBI-S ST ) bearing swallow tails, exhibiting a room temperature columnar hexagonal mesophase with a low clearing point, and high photoluminescence quantum yield, thus making it a promising candidate for efficient OLEDs. Leveraging the luminescent properties of PBI-S ST , a series of OLED devices were fabricated. PBI-S ST was employed as the sole emitter and also incorporated at concentrations of 0.2, 0.5, and 1 wt% in CBP as the host material. Impressively, doped devices employing the compound at 0.2 wt% concentration within the host material CBP displayed an exceptional external quantum efficiency (EQE) of 6.5%. A maximum EQE of 11.6% was observed with 0.5 wt% PBI-S ST in CBP, accompanied by a luminance of 1420 cd m −2 . This notable increase in EQE can be ascribed to energy transfer between the host and guest materials, as well as a hybridized local charge transfer (HLCT) process. The substantial enhancement in EQE marks a significant advancement in the application of multifunctional columnar self-assembled materials for OLED development. Highly fluorescent ambient mesogenic bay S-annulated swallow tail appended perylene bisimide with enhanced electroluminescence breaking the maximum EQE for fluorescent OLEDs in a host-guest configuration with CBP.