1. Enhanced upconversion emission in air using novel stretched poly(vinyl alcohol) thin films
- Author
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Chikanobu Nakamoto, Tomohiro Mori, Akira Fujii, Hitoshi Saomoto, Mori Takeshi, Akane Saito, and Hideyuki Koishi
- Subjects
Vinyl alcohol ,Materials science ,Biomedical Engineering ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Industrial and Manufacturing Engineering ,chemistry.chemical_compound ,Materials Chemistry ,Chemical Engineering (miscellaneous) ,Thin film ,chemistry.chemical_classification ,Aqueous solution ,Process Chemistry and Technology ,Polymer ,Chromophore ,021001 nanoscience & nanotechnology ,Photon upconversion ,0104 chemical sciences ,chemistry ,Chemistry (miscellaneous) ,0210 nano-technology ,Phosphorescence ,Excitation - Abstract
Dense chromophore systems have been proposed as an alternative approach to creating solid-state triplet–triplet annihilation upconversion (TTA-UC) materials. In order to extend this system to polymer-based TTA-UC materials, a new method for the in situ preparation of dense chromophore systems in poly(vinyl alcohol) (PVA) was developed using a mechanical stretching technique. The chromophores used in this study were newly synthesised to dissolve homogeneously in a PVA aqueous solution. These chromophores exhibited a blue upconverted emission in MeOH solution upon excitation with a 532 nm green laser. Remarkably, a clear upconversion emission was observed from the chromophore-blended PVA films even under ambient conditions after the stretching process. In addition, a correlation between the elongation length of the films and the ratio of UC emission/phosphorescence was clearly observed. The stretching process made the chromophores more condensed in the oriented and cross-linked polymer chains, thereby creating favourable conditions for triplet–triplet annihilation.
- Published
- 2018
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