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作者 Chang, Chih-hung
書名 Processing and characterization of copper indium selenide for photovoltaic applications
國際標準書號 9780599597082
book jacket
說明 250 p
附註 Source: Dissertation Abstracts International, Volume: 60-12, Section: B, page: 6231
Chairman: Timothy J. Anderson
Thesis (Ph.D.)--University of Florida, 1999
Polycrystalline CuInSe2 (CIS) and related materials, are promising candidates of low-cost high efficiency solar cells. This thesis describes the applications of phase diagrams to suggest alternative absorber precursor structures, explores the use of Rapid Thermal Processing (RTP), and elucidates the structure of CuInSe2 and related materials
A critical assessment of the thermochemical and phase diagram data for the Se unary, Cu-Se, and In-Se binary systems was performed. This information was used to give an evaluated Cu2Se-In2Se3 pseudobinary phase diagram and suggest liquidus lines in the Cu-In-Se ternary system. The resulting information was used to propose a novel bi-layer precursor structure consisting of a co-deposited In-Se (50 to 55 Se at.%) top layer and a Cu-Se (50 to 55 Se. at.%) bottom layer. This precursor structure was designed to form CIS by reacting a liquid CuSe with a solid InSe phase in the process temperature window erature window 524°C to 611°C. Two different precursor structures were fabricated and tested. The first one consists of the three layers, In4Se3/CuInSe2/Cu 2Se, and the second one was a simple two-layer structure, InSe/CuSe. After RTP, the first precursor structure underwent a liquid-solid reaction and formed large grained CuInSe2 films. It is believed the melting of top In4Se3 layer occurs through a monotetic reaction. The second precursor structure also lead to the formation of large grained CIS (∼5 mum) films, as suggested in the reaction pathway analysis
X-ray Absorption Fine Structure (XAFS) measurements were performed on crystals of CuInSe2 with different compositions close to the 1:1:2 stoichiometry, and CuIn3Se5. It was found that the Cu-Se bond length is independent of the Cu occupation number in this composition range within a length of 0.01 A. Least-square fitting of the Se-K edge EXAFS spectra indicated CuInSe2 consists of Se-centered tetrahedron with an average of 2 Cu and 2 In nearest neighbors. On the other hand, CuIn 3Se5 consists of Se-centered tetrahedron with an average of 0.8 Cu and 2.4 In nearest neighbors. The Cu-Se and In-Se bond lengths were determined to be 2.424 and 2.598 A, respectively. This result directly proves that CuIn3Se5 is indeed a defect tetrahedral structure and suggests it consists of three types of local tetrahedral cationic clusters around each Se: 20% 2Cu + 2In (k = 8), and 40% □ + Cu + 2In (k = 7), and 40% □ + 3 In ( k = 9), where □ denotes vacancy and k denotes the sum of the cation valence electrons
School code: 0070
Host Item Dissertation Abstracts International 60-12B
主題 Engineering, Chemical
Physics, Condensed Matter
Engineering, Materials Science
Alt Author University of Florida
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