Efficient Blue and Yellow Organic Light-Emitting Diodes Enabled by Aggregation-Induced Emission

Venkatramaiah, N. ; Kumar, G. Dinesh ; Chandrasekaran, Yogesh ; Ganduri, Ramesh ; Patil, Satish (2018) Efficient Blue and Yellow Organic Light-Emitting Diodes Enabled by Aggregation-Induced Emission ACS Applied Materials & Interfaces, 10 (4). pp. 3838-3847. ISSN 1944-8244

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Official URL: http://doi.org/10.1021/acsami.7b11025

Related URL: http://dx.doi.org/10.1021/acsami.7b11025

Abstract

A new class of donor–bridge–acceptor (D−π–A) π-conjugated light-emitting molecules comprising carbazole as donor and maleimide (Cbz-MI, Cbz-MI(d)), phthalimide (Cbz-Pth) as acceptor units with phenyl ring as spacer have been synthesized in good yields. These compounds exhibit high quantum yield with three distinct emission colors yellowish-green (Cbz-MI), bright yellow Cbz-MI(d), and sky blue (Cbz-Pth) in the solid state. Single-crystal X-ray and quantum chemical calculations reveals that twisting of the phenyl rings with high torsional angle on maleimide and phthalimide units reduce the effective inter-chromophore electronic coupling, furnish dramatic changes in their photophysical properties in solution and solid states. Intriguingly, Cbz-MI(d) and Cbz-Pth exhibits a unique aggregation-induced blue-shifted emission (AIBSE) due to restricted intramolecular rotation (RIR) process, while Cbz-MI shows red-shifted emission in the solid state. The solvatochromic study reveal that combined RIR and excited state migration augment AIE (aggregation-induced emission) properties. The electrochemical properties reveal that Cbz-MI exhibits high oxidation propensity while Cbz-Pth shows low reduction values. Subsequently, organic light-emitting diodes (OLEDs) were fabricated with a simple three-layer device containing Cbz-Pth and Cbz-MI(d) as emitting layers. Cbz-MI(d) exhibits high performance yellow OLED with an external quantum efficiency exceeding ∼4.1% and a brightness exceeding ∼73915 cd/m2, which is among the best performance reported for bright yellow fluorescence organic light-emitting diodes.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:120512
Deposited On:01 Jul 2021 04:34
Last Modified:01 Jul 2021 04:34

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