硒化銅銦鎵薄膜缺陷對太陽能電池元件特性之影響;Investigations on the defect properties of Cu(In,Ga)Se2 Solar Cells

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/65217

Title:	硒化銅銦鎵薄膜缺陷對太陽能電池元件特性之影響;Investigations on the defect properties of Cu(In,Ga)Se2 Solar Cells
Authors:	林威廷;Lin,Wei-ting
Contributors:	光電科學與工程學系
Keywords:	硒化銅銦鎵;太陽能電池;缺陷;界面;薄膜;CIGS;solar cell;defect;interface;thin film
Date:	2014-07-31
Issue Date:	2014-10-15 14:43:43 (UTC+8)
Publisher:	國立中央大學
Abstract:	高效率硒化銅銦鎵(Cu(In,Ga)Se2, CIGS)薄膜太陽能電池採用共蒸鍍製程，其光電轉換效率可達20.8%，為目前薄膜太陽能電池中最具量產潛力的材料。但共蒸鍍製程難以克服大面積鍍膜的均勻性，為了符合業界量產的考量，因此本研究使用銅銦鎵(Cu-In-Ga, CIG)前驅物濺鍍-硒化法來製作CIGS薄膜。 CIGS薄膜的結晶品質及介面缺陷特性，為高效率電池元件的主要關鍵。在CIGS薄膜結晶部分，本研究藉由控制濺鍍功率及氬(Ar)離子轟擊方法，優化CIG前驅物的元素組成比例(Cu/(In+Ga)=1.2)及結晶相轉換(Cu11(In,Ga)9)，得到晶粒尺寸大於1 μm的CIGS薄膜。 CIGS薄膜電池元件主要分為CIGS/Mo介面及CdS/CIGS介面。在CIGS/Mo介面部分，因硒化製程的關係，會形成高材料能隙且低導電率的硒化鉬(MoSe2)化合物，在電池元件中形成背電場效應。本研究藉由調整CIGS薄膜之Cu/In比例及硒化壓力，控制並優化MoSe2厚度，將電池元件效率從1.4%提升至5.2%。在CdS/CIGS介面部分，CIGS薄膜表面有硒化銅(CuxSe)、銅空缺(VCu)與硒空缺(VSe)等缺陷，本研究藉由使用Cd離子擴散法及電池元件後退火處理，修補CIGS薄膜表面缺陷，並且在CIGS薄膜表面形成n-CIGS:Cd的化合物反轉層，使電池元件形成埋藏式p-n接面，將電池元件效率從3.7%提升至7.3%。 ;Cu(In,Ga)Se2 (CIGS) thin film solar cell has been reported that a 20.8% of efficiency can be achieved using co-evaporation method. However, to using this method it is still difficult to scale up the area of good solar cells. In this study, CIGS thin films were prepared by using Cu-In-Ga (CIG) precursor sputtering-selenization process and then CIGS solar cells can be achieved. For a high performance solar cell, the crystalline qualities and the interface properties of the CIGS film are very important. In this research, the stoichiometric ratio (Cu/(In+Ga)=1.2) and the phase transition (Cu11(In,Ga)9) of the CIG precursors were modified by using a sputtering process and an Ar-ion plasma etching process. The CIGS films with good crystalline properties and large grain size (1 μm) were achieved after the selenization process. During the selenization process, a high band-gap material, MoSe2 compound was formed at the CIGS/Mo interface. The MoSe2 can increase the open-circuit voltaic of the solar cell due to the back surface field effect. However, the high resistivity (101-104Ω-cm) and peeling-off phenomenon at the CIGS/Mo interface were observed. The thicknesses of MoSe2 were modified by controlling the Cu/In ratio and selenization pressure. After the modification, the efficiency of the solar cell can be increased form 1.4% to 5.2%. Another defects generated at the CdS/CIGS interface are CuxSe, Cu vacancy and Se vacancy. The short circuit current of solar cells will be reduced by the interface defects. So, these defects were passivated by using Cd ion soaking and post-annealing treatment. Based on this method, the efficiency of the solar cell can be increased form 3.7% to 7.3%
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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