奈米釩酸鉍釔螢光體之製備及特性鑑定與其在生物顯影及太陽能電池之應用

Abstract

本論文利用簡單、快速的水熱法製備奈米釩酸鉍釔螢光體，並以親水性高分子聚合物作為分散劑輔助反應，本製程可得高純度、分散性良好奈米釩酸鉍釔螢光體，並藉由反應環境中pH 值之改變，成功調控奈米YVO4:Bi3+, Eu3+之粒徑大小及晶體形貌。本研究亦利用電子顯微鏡、傅立葉轉換紅外光譜儀及熱重分析儀對奈米螢光體進行特性分析。螢光光譜研究結果顯示藉由Bi3+與Eu3+稀土離子之間的能量轉移可使YVO4:Bi3+, Eu3+奈米螢光體在紫外光激發下放射619 nm 紅光。此外，本研究亦利用親水性樹枝狀高分子聚乙烯亞胺對奈米螢光體表面進行改質，使其表面帶有胺基而能均勻分散於水溶液中，並可利用此官能基與生物分子鍵結，應用於生物檢測及生物顯影。 此外，本研究亦將此奈米螢光體塗佈於矽基材太陽能電池表面，奈米微結構上，以有效降低太陽光反射，並可利用光譜轉換原理，將太陽能電池無法利用之紫外光轉換為可見光波以提升太陽能電池之光電效率，並評估其應用於綠能產業之潛力。

In this study, a series of water-soluble YVO4:Bi3+,Eu3+ nanophosphors (NPs), with surfaces functionalized by a branch polyethylenimine (BPEI) polymer, has been synthesized via a facile one-pot hydrothermal method. The crystal morphology can be well controlled by tuning the reaction temperature, pH value and molecular weight of capping agent BPEI. The BPEI-coated YVO4:Bi3+,Eu3+ NPs with high crystallinity show broad band excitation in the 250 to 400 nm near ultraviolet (NUV) region and exhibit a sharp-line emission band centered at 619 nm under the excitation of 350 nm. The folic acid (FA) and epidermal growth factor (EGF) were attached on the BPEI-coated YVO4:Bi3+,Eu3+ NPs and exhibited effective positioning of fluorescent nanophosphors toward the targeted folate-receptor over-expressed HeLa cells or EGFR over-expressed A431 cells with low cytoxicity, respectively. These results demonstrate that the ligand-functionalized BPEI-coated YVO4:Bi3+,Eu3+ NPs show great potential as a new generation biological luminescent probe for bio-imaging applications. For solar cell application, the c-Si solar cells showed an enhancement of 4 % in short-circuit current density and approximately 0.7 % in power conversion efficiency when coated with BPEI-coated YVO4:Bi3+,Eu3+ NPs on the textured cell surface. The current experiments conclude that the BPEI-coated YVO4:Bi3+,Eu3+ NPs can not only act as luminescent down-shifting centers in the UV region but also serve as an antireflection coating for improving the power conversion efficiency of the c-Si solar cell.