本研究利用兩次陽極氧化法製備出雙開孔二氧化鈦奈米管陣列(opened-end TiNT-array)薄膜，並將其轉移至FTO透明導電玻璃上製成電極。於進一步表面修飾後，探討此電極於染料敏化太陽能電池(DSSC)、量子點敏化太陽能電池(QDSSC)及光電水分解產氫(water splitting)等光電化學上的應用。在二氧化鈦奈米管陣列的製備上，我們結合了兩步驟的陽極氧化法與草酸之選擇性溶解脫膜後，得到獨立式的opened-end TiNT-array。本研究以此opened-end TiNT-array為電極基礎，且依不同表面修飾又分為TiNP/TiNT-array、CdS/TiNT-array及Mn-doped CdS/TiNT-array，並將其製備成FTO電極來進行後續研究。
在染料敏化太陽能電池研究上，我們期望藉由染料吸附量的增加進而提升DSSC的光電轉換效率。在實驗中，我們改變煆燒氣氛且將二氧化鈦奈米顆粒(TiNP)沉積於TiNT-array表面，將此TiNP/TiNT-array轉移至FTO導電玻璃上，並吸附染料N719製備成DSSC電極。在AM 1.5模擬太陽光照射下(100 mW/cm2)，TiNP/TiNT-array之DSSC電極可得到最佳的光電轉換效率為6.16 %，相較於未沉積TiNP之電極的光電轉換效率大幅提升47 %。其染料吸附量也從0.153 μmol/cm2增為0.193 μmol/cm2，增加了26 %。
在量子點敏化太陽能電池及光電水分解產氫的研究上，為了擴展可見光利用率，我們利用連續離子層吸附反應法(SILAR)沉積CdS於TiNT-array表面，並探討不同煅燒溫度對CdS/TiNT-array之FTO電極應用於QDSSC及水分解光電轉換效率的影響。結果顯示，當煅燒溫度300 oC且披覆上ZnS保護層時，在量子點敏化太陽能電池及光電水分解效率的應用上可達最佳的效率表現，分別為0.72 %及5.99 %。
為了進一步提升光電水分解產氫的效率，我們摻雜錳離子於CdS中，並成功地在TiNT-array上沉積錳摻雜硫化鎘，製成Mn-CdS/TiNT-array。將其轉移至FTO導電玻璃製備成光陽極，應用於水分解其光電轉換效率可達6.17 %，相較於同樣煅燒溫度下製得CdS/TiNT-array之效率5.27 %，有明顯提升20 %。此外藉由紫外-可見光(UV-Vis)吸收光譜及入射單光子-電子轉換效率(IPCE)量測證實了錳摻雜的確有助於增加可見光的吸收。我們進一步以電流-時間圖佐證了Mn-doped CdS中的midgap state有助於減少電子-電洞再結合機率，進而增加整體光電轉換效率。

In this research, the preparation and surface modification of free-standing and opened-end TiO2 nanotube arrays (TiNT-array) on fluorine-doped tin oxide glass were studied for dye-sensitized solar cells (DSSCs), quantum dots-sensitized solar cells (QDSSCs) and solar water splitting. In order to prepare the free-standing opened-end TiNT-array, two-step anodization and oxalic acid treatment were conducted. After these procedures, three parts of experiments according to different ways to modify the surface of TiNT-array were as follows.
In the application of DSSCs, the atmosphere of pre-annealing was adjusted. Furthermore TiO2 nanoparticles (TiNP) were deposited on the surface of TiNT-array to fabricate TiNP/TiNT-array. As compared to the DSSC made of bare TiNT-array, the DSSC made of TiNP/TiNT-array exhibits an enhancement in efficiency from 4.23 % to 6.16 % under AM1.5 simulated sunlight, corresponding to nearly 47% improvement. The deposited TiNP increased the surface area, leading to the larger dye adsorption. The dye adsorption fo TiNT-array and TiNP/TiNT-array were 0.153 μmol/cm2 and 0.193 μmol/cm2, respectively.
In the application of QDSSCs and solar water splitting, CdS quantum dots were coated onto TiNT-array by SILAR method to increase the light harvesting in the visible light region. The effects of calcined temperature and passivation layer on the applications of QDSSC and solar water splitting were investigated. As a result, when CdS/TiNT-array was calcined at 300 °C, the optimum power conversion efficiency was 0.72 % in QDSSC and 5.99 % in solar water splitting.
In order to further enhance the efficiency of water splitting, Mn2+ was doped into CdS quantum dots (Mn-CdS/TiNT-array), and then transferred the Mn-CdS/TiNT-array onto the FTO glass for water splitting photoanode. In the application of water splitting, the efficiency of 6.17% was obtained with Mn-CdS/TiNT-array, which was 20% higher than the efficiency with CdS/TiNT-array. The superior photoelectric characteristics were studied by UV-Vis absorption spectrum, photocurrent-time experiment (J-t) and incident photon-to-current conversion efficiency (IPCE) measurement. The measurement of UV-Vis absorption spectrum and incident photon-to current conversion efficiency (IPCE) shows that Mn2+ can increase the light harvesting in the visible light region. The results of photocurrent-time experiment (J-t) improved that the midgap state in Mn-doped Cds has an positive impact on electron transportation.

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