Pallavi Pragyan, Sk Bahadur, Ahir Palak, Patra Abhijit
Department of Chemistry, Indian Institute of Science Education and Research, Bhopal, India.
Chemistry. 2018 Jan 24;24(5):1151-1158. doi: 10.1002/chem.201704437. Epub 2017 Dec 14.
A simple and cost-effective methodology employing environmentally benign substances for the fabrication of white-light emitting materials is important for practical applications in the field of lighting and display devices. Designing purely organic-based white-light-emitting systems with high quantum efficiency in aqueous media is an unmet challenge. With this objective, a new class of pyridoindole-based hydrophobic fluorophore 6,7,8,9-tetrapropylpyrido[1,2-a]indole-10-carbaldehye (TPIC) was introduced. A strategy of self-assembly using nonionic surfactants was employed to enhance the fluorescence of TPIC in an aqueous medium and was exploited as energy donor. The steady-state and time-resolved emission spectra analysis revealed the micelle-mediated energy transfer from TPIC to Nile red (energy acceptor) leading to tunable fluorescence along with white-light emission. The white-light emitting aqueous solution was obtained with the Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.33, 0.36) and significantly high quantum yield of 37 %. Solid-state white-light emission was achieved retaining the assembly of fluorophores in the form of a gel having the high quantum efficiency of 33 % with CIE coordinates of (0.32, 0.36); close to that of pure white light. The bright white luminescence of the inscription prepared using white-light emitting gel on a solid substrate offers promising applications for full-color flat panel displays.
采用环境友好型物质制备白光发射材料的简单且经济高效的方法，对于照明和显示设备领域的实际应用至关重要。设计在水性介质中具有高量子效率的纯有机基白光发射系统是一项尚未解决的挑战。出于这一目的，引入了一类新型的基于吡啶并吲哚的疏水性荧光团6,7,8,9-四丙基吡啶并[1,2-a]吲哚-10-甲醛（TPIC）。采用非离子表面活性剂的自组装策略来增强TPIC在水性介质中的荧光，并将其用作能量供体。稳态和时间分辨发射光谱分析表明，胶束介导了从TPIC到尼罗红（能量受体）的能量转移，从而产生了可调谐荧光以及白光发射。获得了国际照明委员会（CIE）色度坐标为(0.33, 0.36)且量子产率高达37%的白光发射水溶液。通过保持荧光团以凝胶形式组装，实现了固态白光发射，其量子效率为33%，CIE坐标为(0.32, 0.36)，接近纯白光。使用白光发射凝胶在固体基板上制备的铭文发出的明亮白色发光，为全彩平板显示器提供了有前景的应用。
