含不同羧基數釕金屬錯合物染料之性質及光伏效能研究

Abstract

本研究在於探討吡啶配位基上帶有不同羧基數的釕金屬錯合物染料分子(編號Ru-1A、Ru-11A、Ru-2A、Ru-3A、N3)的吸附行為與光伏效能。首先以NMR、FTIR鑑定染料的結構，並用UV-VIS的光譜測定染料的光學性質。由染料的MLCT吸收峰可以得知，當染料上帶有單邊羧基時會造成吸收峰有藍位移的現象。同時利用AFM、TEM、DLS觀察五種染料的吸附行為，可以發現染料會先形成較大的微胞顆粒在TiO2表面沉降，長時間後皆可均勻覆蓋TiO2表面。接著經由染料的吸附/脫附測試可以得知N3因吡啶配位基帶有四個羧基，容易平躺於TiO2，故單一分子表面積最大，吸附量最小。而其他染料則帶有單邊的羧基，因此會以某個角度吸附於TiO2，投影面積小，因此有較大的吸附量。最後將染料應用於染料敏化太陽能電池元件上，發現N3，Ru-3A，Ru-2A，Ru-11A，Ru-1A 染料的轉換效率分別為7.53%，6.72%，6.08%，4.20%，3.39%，Jsc為19.6mA、17.9mA、14.9mA、10.8mA、6.59mA，隨著染料上的羧基數目減少，轉換效率與Jsc有明顯下降的趨勢。此結果也可經由IPCE來支持。交流阻抗分析、IMVS、IMPS、電量收集分析中亦可以得到當染料上的羧基數目減少時，電子生命週期及流出的電量皆有下降的趨勢。

In this study, we compared the adsorption properties and photovoltaic performance among five ruthenium complex dyes having different number of carboxyl groups, denoted as Ru-1A, Ru-11A, Ru-2A, Ru-3A and N3, which have one, two, two, three and four carboxylic groups, respectively. First, the dyes were characterized by NMR and FTIR. And their optical properties in ACN/t-BuOH solution were studied by UV-VIS spectrascopy. From the UV-Vis spectra, the MLCT absorption peak of the dyes blue-shifts with decreasing the number of carboxylic groups. The adsorption mechanism of the dyes were studied by TEM, DLS, AFM and adsorption/desorption test, which can be concluded by the following results: (1) The dye molecules in the solutions tend to form micelles, which deposited on TiO2 surface in micelle form; with increasing time, the dye molecules lead to a homogeneous surface with an approxmate height of one molecule. (2)Due to N3 had four carboxylic groups, it easily lied in flat form on the TiO2 surface,and thus has the smallest adsorption amount. Other dyes containing one-side carboxyl groups would attach to the TiO2 surface with a tilt and have larger adsorption amount. For the performance of DSSCs with MPN liquid electrolyte, N3, Ru-3A, Ru-2A, Ru-11A, Ru-1A attained power conversion efficiency of 7.53%, 6.72%, 6.08%, 4.20%, 3.39%, and the Jsc were 19.6mA, 17.9mA, 14.9mA, 10.8mA, 6.59mA with decreasing the number o f carboxyl groups. The IPCE, EIS, IMVS, IMPS, Voltage-decay tests also supported the results of Jsc and efficiency.