1.沈積氮化銦奈米粒子於二氧化鈦薄膜上及其於染料敏化太陽能電池和光激發螢光之應用 2. 利用衝擊波管研究乙醇高溫分解的反應速率常數及其反應機制

Abstract

第一部分: 沈積氮化銦奈米粒子於二氧化鈦薄膜上及其於染料敏化太陽能電池和光激發螢光之應用 吾人成功以化學氣相沈積法成長氮化銦奈米粒子於二氧化鈦(TiO2)奈米粒子薄膜及奈米管薄膜(NP and NT films)上，而銦和氮的前驅物分別為三甲基化銦(TMIn)與氨氣(NH3)。藉由改變TMIn流量，在沈積溫度為358 K時，我們觀測到InN/TiO2 NP及NT films在染料敏化太陽能電池(DSSC)上分別有4-23%及3-11%的相對提昇。目前我們取得的最佳電池效率，是在使用厚度為 9 μm的TiO2 NP film，以2 sccm的TMIn與20 sccm的NH3在358 K沈積InN 10分鐘而得，光電轉換效率可成功由6.57%提昇至8.20%。 另外吾人亦發現以溫度523 K沈積InN於TiO2 NP film上時，當激發光源的波長為200 nm時，由所測到的光激發螢光光譜可發現TiO2本身的放光能被InN增強數倍。我們推測此放光增強的原因可能來自於InN與O的特殊接面或者在沈積的過程中增加了TiO2表面的缺陷。

第二部分: 利用衝擊波管研究乙醇高溫的反應速率常數及其反應機制 我們成功地利用活塞式衝擊波管配合氫原子共振螢光吸收系統研究濃度範圍為1-100 ppm的C2H5OH於溫度為1308-1706 K與壓力為1-2 atm下的熱解。反應(1a)產物 CH3+CH2OH與反應(1b)產物C2H4+H2O的分支比可利用CH2OH能迅速裂解出氫原子的特性而可從氫原子濃度隨時間的變化求得。另外，我們成功地在反應(1a)的分支比(f1a)結果中觀測到壓力依存關係，這是首次由實驗中觀察到f1a確實存在明顯的壓力依存關係，其壓力依存關係可由下列式子表示，在溫度為1450 - 1760 K及壓力為1, 1.46 and 2.0 atm時，f1a 分別為 (0.71±0.07) - (830±120)/T, (0.90±0.02) - (1080±30)/T, (1.02±0.10) - (1230±170)/T。將所有的實驗結果整理後，可由下列式子表示 k1a/s-1 = F1a(6.07±0.18) x 10^10 exp[-(23850 ± 750)/T] k1b/s-1 = (1-F1a) (6.07±0.18) x 10^10 exp[-(23850 ± 750)/T] 而 F1a表示為 F1a = (0.308P+0.420) – (399P+451)/T 另外，本論文亦利用氫原子濃度、水分子濃度與一氧化碳三種不同的反應物濃度變化進行比較與分析，建立出C2H5OH熱解的反應機制，並針對熱解中的重要反應進行探討，提高反應的準確性。

Part 1: Deposition of InN Nanoparticles on TiO2 Films for Dye-Sensitized Solar Cell and Photoluminescene Studies The direct deposition of InN over TiO2 nanoparticle and nanotube (NP and NT) films was demonstrated by employing a plasma-enhanced chemical vapor deposition (PECVD) system with trimethyl indium (TMIn) and ammonia (NH3) as indium and nitrogen precursors, respectively. By varying the flow rate of TMIn at 358 K, enhancement in power conversion efficiencies by 4-23% and 1-11% under AM 1.5 illumination was observed for N3 dye sensitized solar cells using the InN deposited TiO2 NP and NT films, respectively. With a 9 μm thick TiO2 substrate, the most improvement of conversion efficiency increased from 6.57% to 8.20% by using 2 sccm of TMIn and 20 sccm of NH3 at 358 K for 10 min InN deposition on the TiO2 NP film. The enhancement by InN deposition can be explained by the improved absorption in the range of 400-500 nm and the increased loading of N3 dye molecules. This study describes the noticeable improvement of DSSC efficiencies by semiconductor nanoparticles deposited on TiO2 NP films. The enhancement of photoluminescence (PL) from anatase TiO2 thin films covered with InN nanoparticles by PECVD can also be observed. The strong PL band observed in the anatase TiO2 thin films with the coated InN may be attributed to the special interface of InN/O and/or more defects generated during the deposition.

Part 2: Shock Tube Study on the Thermal Decomposition of Ethanol The thermal decomposition of C2H5OH highly diluted in Ar (1-100 ppm) has been studied by monitoring H atoms using the atomic resonance absorption spectrometry (ARAS) technique behind reflected shock waves over the temperature range 1308 - 1760 K at pressures: 1, 1.46 and 2 atm. Branching fractions for producing CH3+CH2OH (1a) and H2O+C2H4 (1b) have been examined by quantitative measurements of H atoms produced in the secondary decomposition of the product CH2OH; the pressure dependence of the branching fraction for channel (1a) is obtained by a linear least-squares analysis of the experimental data and can be expressed as f1a = (0.71±0.07) - (826±116)/T, (0.90±0.02) - (1079±34)/T, (1.02±0.10) - (1229±168)/T at P = 1, 1.46 and 2.0 atm, respectively, for T = 1450 - 1760 K. The rate constant obtained in this study is found to be consistent with previous theoretical and experimental results; however, the pressure dependence of the branching fraction obtained in this study is smaller than those of previous theoretical works. The experimental k1 and f1a can be summarized as follows: k1a/s-1 = F1a(6.07±0.18) x 10^10 exp[-(23850 ± 750)/T] k1b/s-1 = (1-F1a) (6.07±0.18) x 10^10 exp[-(23850 ± 750)/T] where, F1a is given by, F1a = (0.308P+0.420) – (399P+451)/T. The observed evolutions of [H], [CO] and [H2O] with time, together with the recent experimental and theoretical results on the kinetic parameters of the important related elementary reactions have been used to construct an extended reaction model for the pyrolysis of C2H5OH and compared with the previously proposed kinetic models.