奈米稀土上轉換釩酸釔螢光體之水熱合成及特性鑑定與其在太陽能電池之應用

Abstract

上轉換螢光體能將長波長光吸收轉換為短波長光輸出，此特性促使其具有應用於生物顯影及太陽能電池光譜轉換層的潛力。此研究中我們利用水熱法成功合成表面包覆聚丙烯酸(PAA)或聚乙烯吡咯烷酮(PVP)之YVO4: Yb3+,R3+ (R: Ho, Er)奈米螢光粉，依摻雜活化劑離子的不同，在980 nm 紅外雷射光激發下分別放射紅光(約650 nm)及綠光(約552 nm)。本論文探討水熱製程中反應時間、溫度、活化劑濃度、包覆劑濃度與pH值等實驗條件最佳化，以期製備高發光效率且具有應用潛之上轉換奈米螢光體，並對其分別進行發光光譜、X-光粉末繞射圖譜、掃描式與穿透式電子顯微鏡、紅外光譜與粒徑分布等量測以了解上述材料的光學性質與微結構特性。 另一方面，本研究將太陽能電池以上轉換奈米YVO4:Yb3+,R3+(R = Er, Ho)螢光體加以修飾，並進行相關光電轉換特性量測，以分別探討此類材料在提昇非晶矽太陽能及染料敏化太陽能電池光電轉換效率之潛力。

Upconversion phosphors are characterized by the conversion of long- wavelength radiation to short-wavelength radiation. Due to unique properties, these phosphors have been investigated as candidates for biological imaging and spectral converter to enhance their conversion efficiency in solar cells. By using hydrothermal synthesis, the research has successfully prepared YVO4:Yb3+,R3+ (R: Ho3+,Er3+) nanophosphors, which emit red (650 nm; R = Ho) or green (552 nm; R = Er) light, respectively, when excited with 980 nm laser. We have attempted to enhance the luminescence efficiency by employing poly acrylic acid (PAA) and poly vinyl pyrrolidone (PVP) as capping agents and optimizing reaction conditions such as temperature, concentration of dopants and pH values. The nanophosphors were further characterized by XRD, PL, FT-IR, DLS, SEM, and TEM techniques. We have demonstrated that YVO4:Yb3+,R3+ upconversion nanophosphors exhibit great potential for efficiency enhancement of both amorphous silicon and dye-sensitized solar cells.