Enhanced upconversion emission in air using novel stretched poly(vinyl alcohol) thin films. Issue 6 (12th September 2018)

• Record Type: Journal Article
• Authors: Mori, Takeshi; Mori, Tomohiro; Saito, Akane; Koishi, Hideyuki; Nakamoto, Chikanobu; Fujii, Akira; Saomoto, Hitoshi
• Is Part Of: Molecular Systems Design and Engineering. Volume 3:Issue 6(2018)
• Page Start: 908
• Page End: 916
• Publication Date: 2018-09-12
• Subjects: Chemistry -- Molecular aspects -- Periodicals; Chemical engineering -- Molecular aspects -- Periodicals; Nanotechnology -- Periodicals; 620.5
• DOI: 10.1039/c8me00041g
• Languages: English
• ISSNs: 2058-9689

Abstract

Abstract : The mechanical stretching process enhances the upconversion emission of chromophore-blended poly(vinyl alcohol) films under an air atmosphere. 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.