Study On The Regulation And Enhancement Of The Luminescence Properties Of Phosphate Photonic Crystals Doped With Rare Earth Ions

Photonic crystals co-doped luminescent center materials have attracted widespread attention.It has great potential applications in lasers,optical fibers,solar cells,biosensors,and displays.Rare-earth ions are widely introduced as luminescence centers because of their advantages of sharp emission,rich spectrum,and good adaptability.However,rare-earth ions also have some drawbacks:for example,the emission of a single rare-earth ion is not monochromatic.Due to the small absorption cross section of the luminescent center,weak emission intensity,the luminescence efficiency of some luminescent centers are low,which limits their practical application.Therefore,the luminescence regulation and the enhancement of the luminescence intensity of the luminescent center have important scientific significance and research value.In this experiment,we propose that the upconversion luminescence of Er³⁺is regulated by inverse opal and photonic crystal heterostructures,and the surface plasmon resonance effect of the noble metal nanoparticles is mainly used to enhance the luminescence of the rare earth ions.The properties and mechanism of their photoluminescence in visible and near infrared were studied.Effects of photonic bandgap,gold and silver nanoparticles on photoluminescence of photonic crystals have been investigated.Photonic crystal heterostructures composed of YbPO₄:Er³⁺inverse opal and polystyrene opal were prepared via a template-assisted process,which exhibited two photonic band gaps.The influence of two photonic band gaps of photonic crystal heterostructure on the upconversion luminescence of YbPO₄:Er³⁺inverse opal was investigated.The upconversion emission suppression caused by single photonic band gap from the following YbPO₄:Er³⁺inverse opal or the upper opal was observed.The upconversion luminescence was strongly suppressed due to the two photonic band gap overlapping effect caused by the following YbPO₄:Er³⁺inverse opal or the upper opal.The modified mechanisms of upconversion luminescence were discussed by the upconversion luminescence lifetime of YbPO₄:Er³⁺photonic crystal heterostructures.The results demonstrated the modified upconversion luminescence is attributed to the photon trapping caused by Bragg reflection of photonic crystal heterostructures.In this work,we present a facile preparation approach of the Au nanoparticles embedded LaPO₄:Eu³⁺inverse opal photonic crystals.In the typical preparation process,the transparent LaPO₄:Eu³⁺sol including HAuCI₄ was infiltrated into the opal templates.After the sintering,the10-20 nm Au nanoparticles were formed in the interior of nano-sized wall of LaPO₄:Eu³⁺inverse opal and the Au nanoparticles embedded LaPO₄:Eu³⁺inverse opals were obtained.The luminescence of Au nanoparticles embedded LaPO₄:Eu³⁺inverse opal was investigated.The emission peaks at the 593,618 and 698 nm from Eu³⁺ions were observed.The 593,618 and 698nm emissions of Au nanoparticles embedded LaPO₄:Eu³⁺inverse opals were enhanced in contrast to these of LaPO₄:Eu³⁺inverse opal without the Au nanoparticles,which is from the excitation field enhancement caused by the localized surface plasmon resonance of the Au nanoparticles.The Ag or Au nanoparticles embedded YbPO₄:Er³⁺inverse opals were prepared.The influence of Ag or Au nanoparticles on the upconversion photoluminescence of YbPO₄:Er³⁺inverse opals was studied,and the upconversion luminescence enhancement induced by the Ag or Au nanoparticles was observed.The mechanisms of upconversion luminescence enhancement of YbPO₄:Er³⁺inverse opals were discussed.YbPO₄:Er³⁺and YbPO₄:Nd³⁺/Er³⁺inverse opal photonic crystals were prepared.The effect of photonic bandgap on the upconversion luminescence of YbPO₄:Er³⁺and YbPO₄:Nd³⁺/Er³⁺inverse opal was studied.The results show that when the Er³⁺emission peak overlaps with the photonic bandgap,the photonic bandgap suppresses the spontaneous emission of Er³⁺,which makes the electron of the visible light level of Er³⁺relaxed to the near-infrared energy level,making the near-infrared emission enhanced.