利用水熱法製備摻雜鋰之氧化鋅奈米線及其性質研究

Preparation and Characterization of Li-doped ZnO Nanofibers by Hydrothermal method

陳靜如(Ching-Ru Chen)

指導教授 ： 洪逸明

元智大學/工程學院/先進能源碩士學位學程/碩士(2011年)

https://doi.org/10.6838/YZU.2011.00213

摘要

本研究利用水熱法(hydrothermal method)成長摻雜鋰之氧化鋅(Li-ZnO)奈米線陣列於透明導電基板上，透過二階段沉積之方式製備Li-ZnO樹枝狀結構，並於樹枝狀奈米線上旋鍍Li-ZnO球型結構，將合成好之Li-ZnO複合結構做為光陽極組裝成染料敏化太陽能電池(Dye-Sensitized Solar Cell，DSSC)，並量測其轉換效率。探討水熱之反應條件對晶體結構及光電性質的影響。水熱過程中，透過聚乙基亞胺的添加能有效抑制奈米線的成長，合成出平均直徑約27 nm之Li-ZnO奈米線，藉由成長時間的控制，於水熱時間4小時下所成長的奈米線，有最大之長寬比數值125。此方法製備之Li-ZnO奈米線為結晶性良好之六方纖鋅礦結構，並沿著[002]方向成長。二階段成長之樹枝狀結構，其平均直徑約27 nm，整體樹枝長度約為22 μm，其成長方向多以[101]方向成長。將此一結果組裝成DSSC，結果得知，鋰的導入能有效提升電池的轉換效率，其轉換效率為1.04 %，利用二次沉積之方式提高整體比表面積，提升染料吸附量，其轉換效率為2.74 %。進一步於樹枝狀結構表層塗佈Li-ZnO球型顆粒，此顆粒能完全填補奈米線縫隙，當入射光進入球型結構時容易產生光散射，延長光行徑距離，減少電子的再次重組，同時提高氧化鋅與染料之間的表面穩定性，使電池的效率倍增，其轉換效率達到3.00 %。此方法製備之Li-ZnO DSSC有最佳的光電轉換效率。

關鍵字

氧化鋅 ； 水熱法 ； 摻雜 ； 染料敏化太陽能電池

並列摘要

In this paper, the Li-ZnO nanofibers and nanoforsets had been synthesized on transparent conducting oxide substrates using a two-step hydrothermal method. The Li-ZnO nanoparticle was synthesized by sol-gel method and spin-coated on the surface of Li-ZnO nanoforests substrate. It was found the average diameter of Li-ZnO nanofibers is about 27nm due to the addition of PEI, which can hinder the lateral growth and only growth along [002] axial. The aspect ratios of the Li-ZnO nanofibers is depend on the growing time, the highest aspect ratio can be obtained with a growing time of 4 hours. Structure analyses of the Li-ZnO nanofibers reveal that the nanofibers is single crystalline wurtzite structure and grow along the [002] direction. The morphology of Li-ZnO nanoforests was uniform by two-step hydrothermal method. The length of the branched Li-ZnO nanoforests is 22 μm upon a single growth step and their diameter is about 27nm. Structure analyses of the Li-ZnO nanofibers revealed that the nanoforests possess polycrystalline wurtzite structure and grow along the [101] direction. These results showed that the conversion efficiency (η) of the Li-ZnO nanofibers DSSC is 1.04 %. Moreover, the electrons transport properties of the Li-ZnO nonaforests based DSSC were compared to that of Li-ZnO nanofibers cell. The conversion efficiency of the Li-ZnO nanoforests DSSC is 2.74 %. Li-ZnO nanoparticles are further bottom-up grown within the interstices of the Li-ZnO nanoforests using a spin-coated method to form the Li-ZnO composite structure. The conversion efficiency of the Li-ZnO composite DSSC is 3.00 %. The slightly higher light-harvesting efficiency in Li-ZnO composite anode is ascribed to its longer electron transport pathway compared to the Li-ZnO nanofibers anode.

並列關鍵字

ZnO ； hydrothermal ； dopping ； DSSC

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