Research Progress of Light Wavelength Conversion Materials and Their Applications in Functional Agricultural Films

Abstract

As new fluorescent materials, light wavelength conversion materials (light conversion agents) have attracted increasing attention from scientific researchers and agricultural materials companies due to their potential advantages in efficiently utilizing solar energy and increasing crop yield. According to the material properties, the light conversion agents can be divided into fluorescent dyes, organic rare-earth complexes, and inorganic rare-earth complexes. The current researches indicates that the fluorescent dyes have relatively high production costs, poor light stability, difficult degradation processes, and easily cause pollution to the ecological environment. The organic rare-earth complexes have short luminescence times, high production costs, and suffer from rapid decreases in luminescence intensity. Compared with fluorescent dyes and organic rare-earth complexes, although rare-earth inorganic complexes have high luminous efficiency, stable chemical properties, and better spectral matching performance, the existing inorganic light conversion agents have relatively poor dispersibility in agricultural films. According to the research on light conversion agents at home and abroad in recent years, this paper first introduces the three common light conversion agents, namely fluorescent dyes, organic rare-earth complexes, and inorganic rare-earth complexes, as well as their uses in agricultural films and their mechanisms of light conversion. At the same time, the preparation methods, advantages, disadvantages, and existing problems of various light conversion agents are classified and explained. Finally, we predict the development trends for light conversion agents in the future by considering six aspects, namely efficiency, cost, compatibility with greenhouse films, light matching, and light transmittance, in order to provide a reference for the preparation of stable and efficient light conversion agent materials.

Keywords: agricultural film; agricultural optics; light conversion; luminescent materials; optical modulation.

Figure 1

Synthesis route of S-triazine compounds.

Figure 2

Synthesis routes of fluorescence dyes 1–4. Adapted with permission from ref. [22]. Copyright 2018 Science Direct.

Figure 3

Photos of polycrystalline powders K-NMI-Eu and K-NMI-Tb exposed to ultraviolet light (λ = 330–380 Nm) under ambient lighting in a room (a,c) and at indoor temperature (b,d). Adapted with permission from ref. [27]. Copyright 2019 Science Direct.

Figure 4

Chemical structures of complexes: (a) Eu₂(TPA)(TTA)₄Phen₂; (b) Eu(TPA)(TTA)Phen. Adapted with permission from ref. [30]. Copyright 2007 Springlink.

Figure 4

Chemical structures of complexes: (a) Eu₂(TPA)(TTA)₄Phen₂; (b) Eu(TPA)(TTA)Phen. Adapted with permission from ref. [30]. Copyright 2007 Springlink.

Figure 5

Diffuse reflectance and UV–Vis absorption spectra of Ca_1.7-ySr(PO₄)₂:0.15Ce³⁺, yMn²⁺, and 0.15Na⁺. Adapted with permission from ref. [38]. Copyright 2017 Royal Society of Chemistry.

Figure 6

Schematic diagram of the experimental process used for SOG/SMS composite films. Adapted with permission from ref. [41]. Copyright 2016 Science Direct.

Figure 7

Photographs of the Moflight conversion material under (a) sunlight and (b) UV light. The foils measured approximately 2 × 2 cm².