Structural, thermal, optical and antibacterial properties of Co-doped (Dy3+/Eu3+): PEG + PVA novel transparent hybrid films

Abstract

In this report, PEG + PVA + Dy3+:Eu3+ films with Eu3+ concentrations of 1-7wt% were prepared by solution casting method and characterized. The composites were characterized by PXRD, FTIR, UV-Vis, DMA, SEM, TGA and photoluminescence measurements, and also their antibacterial activities were tested by the diffusion method. Thermogravimetric analyzes show that increasing Eu3+ content outstandingly increases thermal stability. Moreover, the antibacterial properties of composites showed strong activities against E. coli and S. aureus with the addition of Dy3+ and Eu3+ ions to polymer blends. Optical measurement records presented that the optical band gap E-g progressively decreased from 4.66 eV for the undoped PEG + PVA blend film to 3.18 eV by increasing Eu3+ ions concentration. Charmingly, the room temperature PL results reveal that the enhancement of the emission of Eu3+ ions in the PEG + PVA polymer matrix after co-doping with Eu3+ ions, whereas the reduction of Dy3+ emission intensity, owing to energy migration from Dy3+ to Eu3+. Besides, according with low-temperature PL measurements indicate that the PL density gradually decreases due to thermal quenching as the temperature increases. With the temperature increased, the color coordinates gradually changed from orange to reddish-orange. These results show that Dy3+/Eu3+ doped polymer blends can likely of a promising candidate in varieties of applications including OLEDs, biosensors, polymer solar cells and optoelectronics devices.