【作者】 刘辉；

【导师】 李岳彬；

【作者基本信息】 湖北大学 ， 微电子学与固体电子学， 2018， 硕士

【摘要】 红外光能够与物质之间同时发生光热效应和光电效应,在民用的医学诊断与治疗、遥感成像、工业自动控制、环境监测、光通信等领域及军用的夜视、航海、航空航天以及武器探测等方面有许多应用。980 nm近红外光处于生物组织光谱学窗口内,在生物体成像、光动力治疗和激光手术方面有广阔的应用前景,同时也在工业生产,显示成像等方面有应用。本文采用低成本且高效的有机聚合物材料与上转换荧光材料复合,制备出可探测980 nm近红外光的非制冷红外探测器。本文成功制备了与NaYF4:Yb3+,Er3+荧光纳米晶结合的聚(3-己基噻吩-2,5-二基)(P3HT)的光电导复合膜。NaYF4:Yb3+,Er3+上转换纳米颗粒能将980 nm低光子能量的近红外光转换成可见光发射,而这种发射光恰好能被P3HT有机半导体材料吸收,产生光生载流子增强其导电性。为进一步提升复合薄膜的探测率,在NaYF4:Yb3+,Er3+表面负载Au纳米颗粒,以贵金属等离激元(SPR)增强其荧光。将上转换荧光纳米晶与P3HT结合而成的有机光电导材料以其高效、廉价、便携、低毒、便于大规模制造与集成等优势,有望成为未来光子收集,光子储存和光电晶体管材料的理想选择之一。本文主要研究内容与结果如下:(1)采用热分解法制备出纯β相的NaYF4:Yb3+Er3+稀土上转换纳米晶。本文通过调控表面配体种类和浓度,可控制备了尺寸分别为17 nm和44 nm的球状纳米颗粒和77 nmd盘状纳米颗粒。探究了 980nmNIR激发光功率对三种不同尺寸的NaYF4:Yb3+,Er3+纳米颗粒发光性能的影响。在980 nm连续NIR激光的激发下,纳米晶在528 nm与542 nm处有强烈的绿光荧光,来自于Er3+的2H11/2→4I15/2和4S3/2→4I15/2的跃迁。中心波长为657 nm处的红色荧光来自于Er3+的4F9/2→4115/2的跃迁。在激发功率同为5 W/cm2的980 nm NIR激发下,尺寸为44 nm的NaYF4:Yb3+,Er3+纳米颗粒的绿色荧光强度比17 nm纳米颗粒绿色荧光强度高了 14倍,而尺寸77 nm的纳米颗粒的荧光则是尺寸17 nm的荧光的67倍。进一步研究表明,随着激发光功率密度的增大,三种上转换纳米颗粒的绿光与红光的比例都呈现先升高后下降的趋势。(2)以油胺为还原剂和表面配体成功在NaYF4:Yb3+,Er3+纳米晶表面负载上约9 nm大小的Au纳米颗粒,利用贵金属局域表面等离激元增强上转换荧光。按照NaYF4:Yb3+,Er3+和Au摩尔比0.005:1,0.01:1,0.05:1在NaYF4:Yb3+,Er3+颗粒表面负载Au纳米颗粒,负载Au纳米颗粒的NaYF4:Er3+,Yb3+纳米晶的上转换荧光比未负载Au的样品最多增强了 67%。(3)在有氧化层的硅衬底上制作插指电极,再将负载Au的NaYF4:Er3+,Yb3+纳米颗粒与P3HT混合旋涂于带有电极的衬底上组装成器件。在偏置电压3 V,功率密度为1 W/cm2的980 nm近红外光激发下,器件获得了相对于暗电流6.7倍的传感电流,初步实现了 980nm近红外光的探测。更多还原

【Abstract】 Infrared light can interact with matter to result in photothermal effect and photoelectric effect,which show great potential in medical theranostics,sensing,industrial automatic control,environmental monitoring,optical communications,military night vision,and,aerospace and weapon detection.Especially,the 980 nm near-infrared light located in biological tissue optical window,have been often utilized in the field including biological imaging,photodynamic therapy and laser surgery,and also in industrial production,display imaging.In this paper,a photoconductive composite films composed with NaYF4:Yb3+,Er3+upconversion fluorescence nanocrystals and polymer semiconductor poly(3-hexylthiophene-2,5-diyl)(P3HT)were utilized to perform the detection of 980 nm NIR light.The emission of NaYF4:Yb3+,Er3+nanoparticles excited by 980 nm NIR light,could be absorbed by the P3HT to produce hole-electron pairs,and resulted in current with the external bias.This current were finally enhanced by the plasmonic Au nanoparticles,and could indicate the existence and power of 980 nm NIR light.The organic photoconductive material combining up-converted fluorescent nanocrystals with P3HT is highly efficient,inexpensive,portable,low-toxic,and easy fabrication,and is expected to become an ideal photon collection,photon storage,and phototransistor material in the future.The main content and results of this article are as follows:(1)Pure β phase NaYF4:Yb3+,Er3+ upconversion nanocrystals were prepared by thermal decomposition.In this paper,by adjusting the type and concentration of surface ligands,spherical nanoparticles with sizes of 17 nm and 44 nm and 77 nm were controllably prepared.The effect of 980 nm NIR excitation power on the luminescence of three different sizes of NaYF4:Yb3+,Er3+ nanoparticles were discussed.Under the excitation of 980 nm continuous NIR laser,the nanocrystals had strong green fluorescence at 528 nm and 542 nm,which were due to the transitions of 2H11/2 →4I15/2 and 4S3/2→4I15/2 of Er3+.The red fluorescence at the center wavelength of 657 nm comes from the transition of 4F9/2→4I15/2 of Er3+.Under the excitation of 980nm NIR with the same excitation power of 5W/cm2,the green fluorescence intensity of NaYF4:Yb3+ and Er3+ nanoparticles with size of 44nm was 14 times higher than that of 17nm nanoparticles,and the size of nanoparticle with 77nm was higher.The fluorescence is 67 times that of the 17 nm size.Further studies show that with the increase of the power density of the excitation light,the proportions of the green and red light of the three upconverted nanoparticles appear to increase first and then decrease.(2)Au nanoparticle about 9 nm in size was successfully prepared with oleylamine as a reducing agent and a capping ligand,and based on this,the upconversion fluorescence was enhanced by localized surface plasmon of precious metal.According to NaYF4:Yb3+,Er3+ and Au molar ratio 0.005:1,0.01:1,0.05:1,Na nanoparticles were loaded on the surface of NaYF4:Yb3+,Er3+ particles,and NaYF4:Er3+,Yb3+ on Au nanoparticles were loaded.The upconversion fluorescence of nanocrystals was enhanced by 67%.(3)Fabricating the intercalation electrode on the silicon substrate with oxide layer,and then spin-coating the Au-loaded NaYF4:Er3+,Yb3+ nanoparticles with P3HT onto the substrate.Under the excitation of 980 nm near-infrared light with a power density of 1 W/cm2,the device obtained a current increase of 6.7 times.更多还原