基于阳极氧化铝模板增强NaYF4:Yb^(3+)/Er^(3+)上转换发光研究

Enhancement of NaYF4:Yb^(3+)/Er^(3+)up-conversion luminescence based on anodized alumina template

采用共沉淀法制备了Yb^(3+)/Er^(3+)共掺杂的稀土掺杂上转换纳米晶.并对样品的相结构和形貌进行表征.结果表明:制备的NaYF_(4):Yb^(3+),Er^(3+)具有六方晶相,形貌均一.利用两步阳极氧化法制备了阳极氧化铝模板.通过扫描电子显微镜对样品形貌进行表征,结果表明:制备的阳极氧化铝模板周期性良好,孔径均一.在近红外980 nm激发下,阳极氧化铝模板实现了对上转换纳米晶发光强度的增强,使NaYF_(4):Yb^(3+),Er^(3+)的红绿光发射强度分别增强了4.4倍和9.0倍.运用时域有限差分法探究其增强机制,结果表明主要增强机制为阳极氧化铝模板的局域表面等离子共振效应.接着探究了不同入射角度下模板的发光强度,发现随着入射角度的增大,上转换纳米晶红绿光的发光强度均先减小后增大.本研究为上转换纳米晶在防伪领域和太阳能电池领域的应用提供了参考.

Up-conversion nanoparticle(UCNP)can collect near-infrared(NIR)light and convert it into visible light.Therefore,UCNP has potential applications in fields such as biomedicine,anti-counterfeiting,and solar cells.However,the efficiency of traditional UCNP in the above-mentioned fields is relatively low,greatly limiting its use in related fields.Therefore,enhancing the up-conversion luminescence intensity of up-conversion nanoparticles is particularly important and urgently needed.In this work,anodic alumina templates are used to enhance the luminescence intensity of up-conversion nanocrystals.NaYF_(4):Yb^(3+),Er^(3+)with a diameter of 35 nm is prepared by using co-precipitation method.Single pass AAO templates with pore size and pore spacing of 88 nm and 100 nm are prepared by using two-step anodization method.Finally,NaYF_(4):Yb^(3+),Er^(3+)/AAO composite structures are formed by using spin coating method.The red green light emission intensity of NaYF_(4):Yb^(3+),Er^(3+)/AAO sample can increase 4.4 and 9.0 times that of NaYF_(4):Yb^(3+),Er^(3+)/Al reference sample,respectively.The enhancement mechanism is explored by using the finite difference time domain method,and the results show that the primary source of enhancement is the localized surface plasmon resonance effect of the pores in the anodic alumina template.At the same time,the relationship between the up-conversion luminescence intensity of NaYF_(4):Yb^(3+),Er^(3+)/AAO sample and the incident angle is investigated.The experimental results show that as the incident angle increases,the luminescence intensity of the red and green light of NaYF_(4):Yb^(3+),Er^(3+)/AAO samples first decrease and then increase.Due to the coupling of the local surface plasmon resonance with the excitation wavelength and emission wavelength,the up-conversion luminescence intensity of the sample can be affected.The relationship of AAO channel enhancement factor with incident angle at excitation wavelength and emission wavelength is studied by using the finite difference time domain method.The results indicate that as the incident angle increases,the enhancement factor at the excitation wavelength decreases,while the enhancement factor at the emission wavelength increases after being illuminated at an incident angle of 15°.Therefore,when the incident angle is less than 20°,the electric field intensity at 980 nm dominates,but when it is greater than 20°,the electric field intensity at 540 nm and 650 nm takes precedence.The above results provide a reference for putting them into practical applications in the fields of anti-counterfeiting and solar cells.