- 學位論文
以化學水浴法製備太陽電池硫化鋅奈米晶薄膜之成長探討
Growth Behavior of Nanocrystalline ZnS Thin Films for Solar Cell Using CBD Technique
摘要
摘要 本文主要是以化學水浴法(CBD)沉積硫化鋅(ZnS)薄膜作為銅銦鎵硒(CIGS)太陽能電池之緩衝層，傳統CIGS太陽電池緩衝層為硫化鎘(CdS)，其具有高轉換效率，但Cd為有毒物質，容易對人體造成傷害，需尋求替代材料，而ZnS能隙為3.8eV，較CdS能隙2.4eV為高，ZnS具有高的能隙可增加短波區的透光率提升轉換效率，現今多採用ZnS取代CdS作為CIGS太陽能電池的緩衝層。本實驗以化學水浴沉積法(Chemical Bath Deposition)沉積ZnS作為緩衝層取代CdS，化學水浴沉積法是一種非真空的方法，不僅如此，工作溫度低，製造過程也非常簡單，大大減低了製程的成本。本實驗利用硫酸鋅、硫脲、聯胺、氨水均勻混合後加熱，經由改變前驅物濃度鋅硫比觀察薄膜沉積時間其表面形貌及膜厚大小、退火溫度影響、並觀察緩衝層與CIGS太陽電池疊層關係。 實驗結果發現前驅物濃度鋅硫比1:9所沉積出之薄膜形貌較為緻密，連續膜沉積速率0.88nm/min，XRD分析具有閃鋅礦結構，表面發現平均粗糙度(Rms)約為5.188nm，薄膜透光率在短波區可達到85%以上，退火後發現薄膜吸收邊紅移。在CIGS太陽電池之吸收層疊層ZnS/CIGS/FTO與透光層疊層Al:ZnO/ZnO/ZnS結構中，ZnS膜均可緻密的附著於CIGS膜和ZnO膜上形成良好的異質界面。
並列摘要
Abstract CdS buffer layers deposited by chemical bath deposition (CBD) have been used in high-efficiency Cu(In,Ga)Se2 (CIGS) solar cells. In view of the harmful environmental impact of Cd due to high amount of Cd compound waste from large scale solar cell production, Cd-free buffer layers sho-uld be developed. In this work CBD method was used to deposit nanocrystalline zinc sulfide (ZnS) thin films for CIGS solar cell. The growth behavior containing deposit morphology, growth rate, structure and optical properties of ZnS thin films within 100 nm thickness are investigated by a field emission scanning electron microscope (FE-SEM), Transmission electron microscope (TEM), X-ray diffractometer (XRD), atomic force microscope (AFM) and ultraviolet visible light spectroscope (UV/VIS). The FE-SEM morphologies showed that the impact, even and dense ZnS films were deposited on soda lime glass from solution contained high concentration ratio of Thiourea. The TEM diffraction patterns and XRD patterns revealed that ZnS films were nanocrystalline, of which FCC (111) phase dominated. The plating rate and transmittance of ZnS thin films are 0.8831nm/min and over 85%, respectively. In the CIGS application the TEM morphology revealed that the multilayers of absorber ZnS/CIGS/FTO and Al:ZnO/ZnS had well heterognous intertaces ZnS films were deposited on CIGS layer and ZnO layer with good adhesion, separately.