Optical wavelength conversion element containing ionic liquid, and article equipped with said optical wavelength conversion element

Abstract

Provided is an optical wavelength conversion element which has high optical wavelength conversion efficiency and therefore can be applied to weak light having an intensity similar to that of solar light and also has good long-term stability, and therefore can be used suitably in a solar cell, a photocatalyst, a photocatalyst-type hydrogen / oxygen generation device, a light up-conversion filter and the like. The optical wavelength conversion element is produced by dissolving and / or dispersing both an organic photosensitizing agent (A) and an organic luminescent molecule (B), i.e., a combination that exerts a triplet-triplet annihilation process, in an ionic liquid (C), and is homogeneous and transparent when observed with naked eyes. The ionic liquid (C) has such a property that, when the ionic liquid (C) is washed with superpure water in a volume that is 9 folds the volume of the ionic liquid (C), the water obtained after the washing has a pH value of 5 or more.

Description

technical field [0001] The present invention relates to a light wavelength conversion element containing an ionic liquid and an article (solar cell, photocatalyst, photocatalyst type hydrogen-oxygen generator, and optical upconversion filter) containing the light wavelength conversion element. Background technique [0002] In the face of strong demand for alternative energy sources such as countermeasures against global warming and clean energy, the development of technologies for efficiently converting sunlight into secondary energy sources (electricity, hydrogen, etc.) is urgently needed. For solar cells with high photo-secondary energy conversion efficiency (conversion efficiency from light to secondary energy), photocatalysts for hydrogen production and other photo-secondary energy conversion elements (elements that convert light into secondary energy) Expect to improve. In ordinary solar cells, hydrogen-producing photocatalysts, and other light-secondary energy convers...

AI Technical Summary

Problems solved by technology

However, highly volatile media such as volatile organic solvents and styrene oligomers have safety problems due to flammability, and resin materials that dissolve in the media or swell due to penetration of the media cannot be used for The container of the optical wavelength conversion element is also a problem

[0015] In addition, in an optical upconverter using a TTA process in which a polymer such as cellulose acetate or soft rubber is used as a medium (Patent Document 2 and Non-Patent Documents 2 and 3), the polymer compound is flammable. It is solid at normal temperature (300K) and has low fluidity, so at room temperature (300K) and below room temperature, there are problems such as a significant decrease in the intensity of up-converted light.

Non-Patent Document 3 records that for light upconversion using the TTA process, organic molecules carrying triplet excitation energy in the medium need to perform diffusion motion and collide with each other to exchange energy between organic molecules. Therefore, Although the up-conversion luminescence intensity increases in the temperature range where the temperature is high and the polymer has sufficient fluidity (>300K), the up-conversion luminescence intensity is very weak in the temperature range (≤300K) where the temperature is low and the fluidity of the medium is poor.

[0016] As a means to solve the above-mentioned problems, the present inventors propose a light wavelength conversion element which is formed by dissolving and / or dispersing organic photosensitive molecules and organic light-emitting molecules in an ionic liquid in light upconversion using a TTA process. Obtained and solved existing problems such as decrease in up-converted light intensity due to high viscosity of the medium, flammability of the medium, and volatility of the medium (Patent Document 3)

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