以熱注射法合成高品質銅鋅錫硫奈米粒子及其生長機制之探討

Study on the growth mechanism of high quality Cu2ZnSnS4 nanoparticles synthesized by hot injection method

黃茂誠(Mao-Cheng Huang)

指導教授 ： 賴志煌

國立清華大學/工學院/材料科學工程學系/碩士(2013年)

摘要

目前世界上效率最高的薄膜太陽能電池Cu(In,Ga)Se2(CIGS)已達到20%，但是CIGS中的銦及鎵為稀有金屬，因此，另一種具有潛力的新穎四元化合物半導體材料Cu2ZnSnS4(CZTS)被提出來要取代CIGS。CZTS具有高吸收係數，為直接能隙之半導體，能隙為1.5eV，組成的四種元素銅、鋅、錫、硫皆為地表上富含的元素而且是一個無毒材料。
不同於CIGS的是，目前CZTS的最高元件效率是溶液聯胺法來製備，但因為聯胺是一種毒性且不穩定的化合物，因此，本研究使用熱注射法來合成CZTS奈米粒子。
我們成功的利用熱注射法合成高品質之CZTS奈米粒子，藉由調控反應參數來探討熱注射法中CZTS的生長機制。我們由TEM觀察不同反應條件所生成的CZTS之粒徑大小，並由LaMer model去解釋在熱注射法中奈米粒子的成核及成長過程。我們也藉由XRD及拉曼光譜來鑑定CZTS，我們在拉曼光譜上發現CZTS的結晶性會隨不同的反應條件而有所不同，不同於一般的熱注射法，我們緩慢的注射前驅物來得到高品質之CZTS，我們提出結晶性的不同是因為反應可能分別傾向Ostwald ripening及oriented attachment的生長機制。另外，我們也在XRD上觀察到Wurtzite及kesterite結構之CZTS會在熱注射法中共存。

關鍵字

銅鋅錫硫奈米粒子 ； 熱注射法 ； LaMer模型 ； 生長機制 ； 薄膜太陽能電池

並列摘要

The highest efficiency Cu(In,Ga)Se2(CIGS) thin film solar cells have reached 20%. However, the indium and gallium are rare elements in the crust. A promising quaternary semiconductor Cu2ZnSnS4(CZTS) has been proposed to replace CIGS. CZTS is composed of four earth abundant elements, and has some advantages such as high absorption coefficient, direct band gap of 1.5eV, and nontoxic material.
The highest CZTS device was fabricated by the solution based hydrazine process. However, hydrazine is a vary toxic and unstable compound, so we choose the hot injection method to synthesize CZTS nanoparticles.
We have successfully synthesized high quality CZTS nanoparticles by the hot injection method, and we discussed the CZTS growth mechanism via tuning reaction conditions. We used TEM to observe the size of different nanoparticles, and explained its nucleation and growth mechanism by LaMer model. We also measured CZTS by using XRD and Raman spectrum to identify its structures and phases, and we found that different crystallinity in different reaction condition. Different from other hot injection methods, we used slow injection synthesis to get the high quality CZTS, and we proposed a possible reason to explain why the CZTS nanoparticles possessed different cystallinity. Ostwald ripening and oriented attachment are two mechanisms which may result in different crystallinity during the growth. Moreover, we also observed wurtzite and kesterite CZTS would coexist in the hot injection synthesis.

並列關鍵字

CZTS nanoparticles ； Hot injection ； LaMer model ； Growth mechanism ； Thin film solar cells

參考文獻

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