Metal Nanoparticles Enhance The Luminescence Properties And Mechanism Of Rare Earth Ion Doped Tellurite Glass

Rare earth doped luminescent glass has a wide application prospect in laser,optical amplifier,optical communication and display,but its application is limited due to its low luminescence efficiency.Adding metal nanoparticles in rare earth doped glass can enhance its luminescence properties,but the enhancement mechanism of metal nanoparticles in enhancing the luminescence of rare earth doped glass is not completely clear,which restricts its practical application to some extent.This paper chooses the ion exchange method and high temperature melting method to introduce metal nanoparticles into rare-earth doped tellurite glass,and to investigate the effect of metal nanoparticles on the photoluminescence of rare-earth doped luminescent glass.Firstly,rare earth doped tellurite glasses were prepared by high-temperature melting method and the luminescence properties of Eu³⁺/Dy³⁺single-doped and co-doped tellurite glasses were comprehensively studied.The results demonstrated that the tellurite glasses single doped with Dy³⁺and Eu³⁺exhibited the yellow and red emission under the excitation of UV and blue light,respectively.For the tellurite glasses co-doped with Dy³⁺and Eu³⁺,the energy transfer from the Dy³⁺to the Eu³⁺ions was observed due to the electric dipole-dipole interaction,and the tunable luminescence was obtained by changing the Eu³⁺concentration.Therefore,the light-emitting diodes were constructed by coupling Dy³⁺and Eu³⁺codoped tellurite glasses with the UV or blue chip,and the chromaticity coordinate of such LEDs can be well tuned to white light region.These results indicated that the Dy³⁺and Eu³⁺co-doped tellurite glasses can act as a promising candidate for the blue and UV converted WLEDs.Subsequently,silver was introduced into Eu³⁺/Dy³⁺single-doped and co-doped tellurite glass by ion exchange method.The effect of different ion exchange condition parameters on the state of silver and the effect of the state of silver on the emission properties of rare earth doped tellurite glass were studied.The results show that the state of silver in tellurite glass is always silver nanoparticles under different ion exchange conditions and the different PL enhancement factors of tellurite glasses single-doped with Eu³⁺and Dy³⁺can be obtained by adjusting the overlapping relationship between excitation or emission wavelength and the LSPR of Ag NPs.When the excitation wavelength is overlapped with the LSPR of Ag NPs,the larger enhancement factor was obtained in the Eu³⁺doped tellurite glasses due to the excitation field enhancement.When the emission wavelength is overlapped with the LSPR of Ag NPs,the selective enhancement of 485 nm emission of Dy³⁺was obtained due to the increasing of radiative decays rate besides the excitation field enhancement.The energy transfer enhancement from Dy³⁺to Eu³⁺caused by the LSPR of Ag NPs was also observed in the Dy³⁺and Eu³⁺co-doped glasses.In addition,in order to investigate the difference in the enhancement mechanism of the luminescence caused by the gold and silver nanoparticles,the gold and silver nanoparticles were introduced into the Eu³⁺single doped germanate glass by high-temperature melting method.The results indicate that the excitation field enhancement caused by the Ag nanoparticles was responsible for the luminescence enhancement of the Ag single-existing tellurite glasses doped with Eu³⁺.The enhanced luminescence mechanism of the Au nanoparticle single-existing tellurite glasses doped with Eu³⁺was from the increasing of radiative decays rate caused by the Au nanoparticles.At the same time,it was found that the gold nanoparticles form an ultra-wideband plasmon resonance absorption peak,which has great practical significance for improving the upconversion properties of rare earth ions.The results show that this broad plasmon resonance of gold can enhance the up-conversion visible luminescence and near-infrared luminescence of Er³⁺,Yb³⁺,Nd³⁺doped tellurite glasses and the enhancement at671 nm is stronger than that at 554 nm and near-infrared region,which is due to the better overlap with plasmon resonance absorption of Au nanoparticles.