| The light conversion efficiency of light conversion film?LCF?was limited by the low absorption for short wavelength ultraviolet light of light conversion agent?LCA?.Therefore,according to the influence mechanism of ligand on UV absorption capacity and light conversion efficiency of LCA,a novel light conversion agent LCA-D with high light conversion efficiency was synthesized for the first time by the coordination reaction of Eu3+and the new organic ligand with strong absorption of short UV,?-thujaplicin??-T?.Meanwhile,a novel light conversion film LCF-D was prepared based on LCA-D and its field application experiment evaluation was carried out.The study content and results are as follows:?1?.A novel lanthanide organic complexes[Eu?TTA?2Phen??-T?]?LCA-D?containing Eu3+ions,thenoyltrifluoroacetone?TTA?,1,10-phenanthroline?Phen?,and?-thujaplicin??-T?have been fabricated.Their fluorescence features were compared with Eu?TTA?3Phen?LCA-C?,which is a well-known light-emitting materials among?-diketones light conversion agent.The molecular and crystalline structures of complexes LCA-C and LCA-D were explored using nuclear magnetic resonance spectroscopy?1HNMR?,Fourier transform infrared spectroscopy?FTIR?,and X-ray powder diffraction?XRD?.The optical properties of these complexes were also explored using ultraviolet–visible spectroscopy?UV–Vis?,fluorescence spectra,and absolute photoluminescence quantum yield?PLQY?.Results showed that LCA-D had a wide UV absorption range and higher light conversion efficiency.LCA-D possessed an intense absorption peak at wavelength about 239 nm and a weak absorption peak within a spectral range 250?375 nm with respect to LCA-C.LCA-D possesses a sharp red emission at?=615 nm upon excitation at?=348nm.After the addition of?-T,the intensity of emission peak at?=700 nm has been enhanced for LCA-D. Meanwhile,the magnitude of QY for LCA-D was equal to about 23.91%,which was at least 11.4%higher than that of LCA-C.Besides,the thermal features tested for TG/DTG/DSC also indicated that LCA-D exhibited promising temperature stability at ambient temperature up to 280?,which was suitable for agricultural film processing.?2?.Based on LCA-D,the light conversion film LCF-D were obtained by blow molding through mixed the light conversion master-batch and low-density polyethylene?LDPE?.Their XRD,UV-Vis,PL,PLQY and antibacterial performance were analyzed and compared with PE and LCF-C.Results showed that LCF-C and LCF-D had a stronger UV absorption than PE.In particular,the absorption peak of LCF-D for UV-A was 338 nm,which had a blue shift with respect to LCF-C,indicating that LCF-D had a stronger absorption of short UV wavelength.Both two LCF had a red emission when excited by UV light,and the magnitude of PLQY for LCF-D was 13.67%,which was 29.47%lower than LCF-C.Besides,the excitation spectrum of LCF-D had a blue shift of 4 nm.Besides,the result of XRD showed that the crystallinity of LCF was lower than that of PE,and it's LCF-D,LCF-C,PE from low to high.?3?.Taking the strawberry as test material,the effect of LCF-D on greenhouse temperature,strawberry photosynthesis,growth and yield were studied compared with PE and LCF-C.The results showed that LCF-D could increase average daily indoor temperature by 0.7?and accumulated temperature during growth period in green house by 75.2?compared with PE;While LCF-C could increase daily indoor temperature and accumulated temperature by 0.05?1?and 8.1?only in the first 40 d after films covering.During the early flowering and full productive-initial maturity stage,the photosynthesis rate of strawberry treated with LCF-D were 5.4%and 4.0%higher than PE,respectively,while that of LCF-C treatment was lower than that of PE.Besides,LCF-C and LCF-D treatment could remarkably increase above-ground biomass of strawberry 57.4%and 19.4%,respectively.Meanwhile,LCF-C and LCF-D could obviously improve the yield of strawberry in the early picking stage,which were 31.3%and 48.8%higher than PE treatment.While the differences were not significant. |
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