本論文是以雙重堆疊(bi-layer)製作CIGS為吸收層之薄膜太陽能電池，電池結構為SLG/Mo/CIGS(bi-layer)/CdS/i-ZnO/AZO/Ag，主吸收層Cu(In,Ga)Se2製作流程先在背電極Mo上以Sputter濺鍍CuGa金屬層，以熱蒸鍍機作第一次硒化後，XRD分析發現CuGa金屬層硒化後形成CuGaSe2，並在CuGaSe2/Mo界面形成MoSe2化合物，試片再以Sputter共濺鍍CuInGa金屬層，以熱蒸鍍機完成第二次硒化製程，XRD分析得到Cu(In,Ga)Se2結晶相，實驗結果MoSe2化合物有助於CIGS/Mo界面形成歐姆接觸。試片接著沉積CdS、i-ZnO及AZO層，最後濺鍍銀電極，完成以雙層堆疊CIGS吸收層之太陽能電池。完成的太陽能電池以太陽光模擬器AM1.5G光譜，光強度100(mW/cm2)量測得到Voc開路電壓0.14V，JSC電流密度為6.49(mA/cm2)，Fill-Factor填充因子為28.69%，光電轉換效率為0.26%，本實驗所沉積背電極Mo片電阻為6.76 Ω/square，高於文獻所提0.1Ω/square，對電荷收集有負面影響，而主吸收層厚度目前約500nm，遠低於標準1.5μm～2μm，轉換效率受到限制，因此未來應該針對Mo片電阻及主吸收層厚度加以改善，以提升光電轉換效率。

A bi-layer CIGS film was used as the absorber layer to fabricate solar cell. The structure of the solar cell is SLG/Mo/CIGS(bi-layer)/CdS/i-ZnO/AZO/Ag. Two layers of CIGS films were prepared using CuGa and CuInGa metallic precursors involving both sputtering and selenization process. The metallic precursor of CuGa alloy was deposited onto Mo coated soda-lime glass substrate by sputtering using a Cu-Ga mixture target. Subsequently, the precursor was selenized under Se atmosphere by evaporator. The XRD patterns show that the CuGaSe2 film was found to be single phase while the MoSe2 peak was observed. The MoSe2 layer was suggested that the CIGS /Mo interface with this layer makes a favorable ohmic contact. As the CuGaSe2 was formed, a CuInGa metallic precursor layer was deposited on it using co-sputtering, followed by a selenization process in evaporator system. The crystalline of the selenized film was determined by XRD, and it shows that the single phase Cu(In,Ga)Se2 was observed. Finally, the CdS, i-ZnO , AZO and Ag were deposited on CIGS film in sequence.
The cell was measured under the standard condition of AM1.5G spectrum (100 mW/cm2) at 25oC.The device parameters are as follows: open-circuit voltage (VOC) = 0.14V, short-circuit current density (JSC)= 6.49mA/cm2, fill factor (FF) = 28.69%, and efficiency = 0.26%.
In this study, the sheet resistance of Mo back contact is 6.76 Ω/square. It is higher than the recorded 0.1Ω/square, and decrease the collection of carriers. The thickness of CIGS absorber layer is only 500 nm. The thickness is not efficient to absorb completely solar spectrum. A lower sheet resistance of Mo back contact and a thicker absorber layer are suggested to enhance the conversion efficiency.

[1]Selya Price and Robert Margolis,"2008 Solar technologies market report", National Renewable Energy Laboratory,
NREL/GO-102010-2867,p.57,(2010).
[2]蔡進譯,"超高效率太陽電池從愛因斯坦的光電效應談起",物理雙月刊,二十七卷五期,p.706-708,(2005).
[3]戴寶通,鄭晃忠,"太陽能電池技術手冊",台灣電子材料與元件協會,新竹
,p.6-342,(2008).
[4]Antonio Luque and Steven Hegedus,"Handbook of photovoltaic science and engineering".John Wiley & Sons,New York,(2003).
[5]F.Hergert,S.Jost,R.Hock and M.Purwins,"A crystallographic
description of experimentally identified formation reactions of Cu(In,Ga)Se2",Journal of Solid State Chemistry
,179,p.2394–2415,(2006).
[6]顧鴻濤,"太陽能電池元件導論",全威圖書有限公司,台北縣,p.235- 239,(2008).
[7]M.A. Contreras, T.Nakada, M.Hongo, A.O. Pudov and J.R. Sites," ZnO/ZnS(O,OH)/Cu(In,Ga)Se2/Mo SOLAR CELL WITH 18.6% EFFICIENCY",3rd World Conference on Phorovolraic Energv Conversion,Osaka,p.570,(2003).
[8]R.N. Bhattacharya and K. Ramanathan, "Cu(In,Ga)Se2 thin film solar cells with buffer layer alternative to CdS",
Solar Energy,77,p.679-683,(2004).
[9]C. Platzer-Björkman and T. Törndahl,"Zn(O,S) buffer layers by atomic layer deposition in Cu(In,Ga)Se2 based thin film solar cells: Band alignment and sulfur gradient
",JOURNAL OF APPLIED PHYSICS,100,044506,p.1-9,(2006).
[10]Raghu N. BHATTACHARYA, Miguel A. CONTRERAS and Glenn TEETER, "18.5% Copper Indium Gallium Diselenide (CIGS) Device Using Single-Layer Chemical-Bath-Deposited ZnS(O,OH)", Japanese Journal of Applied Physics,43,11B,p.1475-1476,(2004).
[11]N.Barreau, J.Lähnemann, F.Couzinié-Devy, L.Assmann, P.Bertoncini and J.Kessler"Impact of Cu-rich growth on the CuIn1-xGaxSe2 surface morphology and related solar cells behaviour",Solar Energy Materials & Solar Cells,93,p.2013-
2019,(2009).
[12]O.Volobujeva, M.Altosaar, J.Raudoja, E.Mellikov, M.Grossberg, L.Kaupmees and P.Barvinschi, "SEM analysis and selenization of Cu–In alloy films produced by co-sputtering of metals",Solar Energy Materials & Solar Cells,93,p.11-14,(2009).
[13]Wei Li, Yun Sun, Wei Liu and Lin Zhou,"Fabrication of Cu(In,Ga)Se2 thin films solar cell by selenization process with Se vapor",Solar Energy,80,p.191-195,(2006).
[14]Fangdan Jiang and Jiayou Feng," Effect of temperature on selenization process of metallic Cu–In alloy precursors
",Thin Solid Films,515,p.1950-1955,(2006).
[15]Ho Keun Song, Soo Gil Kim, Hyeong Joon Kim, Suk Ki Kim, Ki Wan Kang, Jung Chul Lee and Kyung Hoon Yoon,"Preparation of CuIn1-xGaxSe2 thin films by sputtering and selenization process ",Solar Energy Materials & Solar Cells,75,p.145-153,(2003).
[16]Ho Keun Song, Jae Kyeong Jeong, Hyeong Joon Kim, Suk Ki Kim and Kyung Hoon Yoon,"Fabrication of CuIn1-xGaxSe2 thin film solar cells by sputtering and selenization process",Thin Solid Films,435,p.186-192,(2003).
[17]V.F. Gremenok, E.P. Zaretskaya, V.B. Zalesski, K. Bente
, W. Schmitz, R.W. Martin and H. Moller," Solar Energy Materials & Solar Cells,89,p.129-137,(2005).
[18]T.Nakada, M.Mizutani, Y.Hagiwara and A.Kunioka,"High efficiency Cu(In,Ga)Se2 thin film solar cells with a CBD-ZnS buffer layer", Solar Energy Materials & Solar Cells
,67,p.255-260,(2001).
[19]Tokio NAKADA and Masayuki MIZUTANI,"18% Efficiency Cd-Free Cu(In,Ga)Se2 Thin-Film Solar Cells Fabricated Using Chemical Bath Deposition (CBD)-ZnS Buffer Layers",
Jan.J.Appl.Phys,41,p.165-167,(2002).
[20]K.Sakurai, R.Hunger, N.T suchimochi, T.Baba, K.Matsubara
,P.Fons, A.Y amada, T.Kojima, T.Deguchi, H.Nakanishi and S.Niki, "Properties of CuInGaSe2 solar cells based upon an improved three-stage process",Thin Solid Films,431-432,p.6-10,(2003).
[21]D.Braunger, D.Hariskos, G.Bilger, U.Rau and H.W. Schock,
"Influence of sodium on the growth of polycrystalline Cu(In,Ga)Se2 thin films",Thin Solid Films,361-362,p.161
-166,(2000).
[22]T.Wada, N.Kohara, S.Nishiwaki and T.Negami,
"Characterization of the Cu(In,Ga)Se2/ Mo interface in CIGS solar cells",Thin Solid Films,387,p.118-122,(2001).
[23]Tom Markvart and Luis Castañer,"Solar Cells: Materials, Manufacture and Operation",Elsevier Science LTD,Oxford, p.
332,(2005).
[24]Michael Bass,"Handbook of Optics, Third Edition Volume II: Design, Fabrication and Testing, Sources and Detectors, Radiometry and Photometry",vol.2,2nd ed.,McGraw Hill Professional,New York,(1994).
[25]劉博文,"光電元件導論",全威圖書有限公司,台北縣,p.2-11,(2005)
[26]S. Ishizuka, K. Sakurai, A. Yamada, K. Matsubara, P. Fons, K. Iwata, S. Nakamura, Y. Kimura, T. Baba, H. Nakanishi, T. Kojima and S. Niki,"Fabrication of wide-gap Cu(In1-xGax)Se2 thin film solar cells: a study on the correlation of cell performance with highly resistive i-ZnO layer thickness", Solar Energy Materials & Solar Cells,87,p.541-548,(2005).
[27]Shunsuke Kijima and Tokio Nakada,"High-Temperature Degradation Mechanism of Cu(In,Ga)Se2-Based Thin Film Solar Cells",Applied Physics Express,1,p.075002,(2008).
[28]汪建民,"材料分析",中國材料科學學會,新竹市,p.121-122,(1998)
[29]陳力俊,"材料電子顯微鏡學",儀科中心出版,p.352-389,(1994).
[30]林麗娟,X光繞射原理及其應用,工業材料,86期,p.100,(1994).
[31]John H. Scofield, A. Duda, and D. Albin,"Sputtered Molybdenum Bilayer Back Contact for Copper Indium Diselenide
-Based Polycrystalline Thin-Film Solar Cells",Thin Solid Films, 260,1,p.26-31,(1995).