Light-upconversion film is stable in air, easy to manufacture

March 14, 2019
Light-converting chromophores are embedded in a polyvinyl alcohol film that is stretched to orient the chromophores.
(Image: WINTEC) Researchers at the Industrial Technology Center of Wakayama Prefecture (WINTEC; Ogura Wakayama, Japan) have developed and obtained a patent for a new, more-robust light upconversion film to convert low-energy to high-energy photons. In their experimental example, the film converted laser light at a 532 nm wavelength to blue light.1 Previous light upconversion films were not stable in air and were made at least in part of a liquid or semisolid, so this was a difficult technology to work with. Others require the fabrication of complex heterostructures. At WINTEC's Industrial Technology Center, the group succeeded in developing a film that causes stable light upconversion even in the air by confining the light-upconversion chromophores in a polyvinyl alcohol film and stretching the film to make the chromophores mre condensed within the oriented and cross-linked polymer chains. The chromophores upconvert light via triplet–triplet annihilation. The researchers say that large areas of this film can be easily manufactured in the future. The film will be used with photovoltaic cells and energy-saving surfaces. The achievement is the result of the R&D project "Core Technology Establishment Project (FY1999-2001)" at the Industrial Technology Center. Source: REFERENCE: 1. Takeshi Mori et al., Molecular Systems Design & Engineering (2018);

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