Efficient white-light emission from a single polymer system with "spring-like" self-assemblies induced emission enhancement and intramolecular charge transfer characteristics. Issue 19 (4th May 2017)

• Record Type: Journal Article
• Authors: Ravindran, Ezhakudiyan; Somanathan, Narayanasastri
• Is Part Of: Journal of materials chemistry. Volume 5:Issue 19(2017)
• Page Start: 4763
• Page End: 4774
• Publication Date: 2017-05-04
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c7tc01036b
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : A new strategy of "spring-like" self-assemblies induced efficient and pure white-light emission from a single-layer device architecture by using a dopant–host copolymer system. Abstract : Over the past few decades, aggregation-induced emission enhancement (AIEE) has been marked as a powerful tool to offset the bottleneck problem of the aggregation-caused quenching (ACQ) effect in organic light-emitting diodes (OLEDs). However, the application of fluorophores with AIEE properties to enhance the efficiency of non-doped white-light-emitting single-layer polymers is scarce. However, we report herein a novel orange-red emitting multifunctional organic fluorophore consisting of two terminal attachments of push–pull moieties separated by a biphenyl free rotor named BPPTA and its copolymers. A high photoluminescence quantum yield ( Φ PL ) of 69.1% was observed for BPPTA with strong intramolecular charge-transfer (ICT) and AIEE characteristics. A meticulous investigation showed that the enhanced emission in the solid state was due to the formation of "J-aggregates" with ordered supramolecular self-assembly. Interestingly, BPPTA 0.1 exhibited a unique ordered "spring-like" supramolecular self-assembly and a significant reduction in charge trapping due to its ambipolar charge-transport nature. As a result, pure and efficient white-light emission with Commission Internationale de l'Eclairage (CIE) coordinates of (0.32, 0.33) and maximum luminance, current and power efficiencies of 15 672 cd m −2, 9.30 cd A −1 and 7.98 lm W −1, respectively, were displayed. The DFT and TD-DFT analyses of the BPPTA-gen and copolymer model systems strongly typified the presence of intramolecular charge transfer (ICT) characteristics. This was hitherto one of the best polymer system for dopant–host non-doped single-layer two-colour polymer white organic light-emitting devices (PWOLEDs).