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PREPARATION OF EFFICIENT CUIN1-XGAXSE2-YSY/CDS THIN-FILM SOLAR CELLS BY OPTIMIZING THE MOLYBDENUM BACK CONTACT AND USING DIETHYL
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TitlePREPARATION OF EFFICIENT CUIN1-XGAXSE2-YSY/CDS THIN-FILM SOLAR CELLS BY OPTIMIZING THE MOLYBDENUM BACK CONTACT AND USING DIETHYL
AuthorKadam, Ankur
Keywordsthin-film
CIGS
CIGSS
molybdenum
diethylselenide
solar cells
AbstractHigh efficiency CuIn1-xGaxSe2-ySy (CIGSS)/CdS thin-film solar cells were prepared by optimizing the Mo back contact layer and optimizing the parameters for preparing CIGSS absorber layer using diethylselenide as selenium source. The Mo film was sputter deposited on 2.5 cm x 10 cm soda-lime glass using DC magnetron sputtering for studying the adhesion and chemical reactivity with selenium and sulfur containing gas at maximum film growth temperature. Mo being a refractory material develops stresses, nature of which depends on the deposition power and argon pressure. It was found that the deposition sequence with two tensile stressed layers deposited at 200W and 5 x 10-3 Torr argon pressure when sandwiched between three compressively stressed layers deposited at 300 W power and 0.3 x 10-3 Torr argon pressure had the best adhesion, limited reactivity and compact nature. An organo-metallic compound, diethylselenide (DESe) was developed as selenium precursor to prepare CIGSS absorber layers. Metallic precursors Cu-In-Ga layers were annealing in the conventional furnace in the temperature range of 475oC to 515 oC and in the presence of a dilute DESe atmosphere. The films were grown in an indium rich regime. Systematic approaches lead to the optimization of each step involved in the preparation of the absorber layer. Initial experiments were focused on obtaining the range of maximum temperatures required for the growth of the film. The following experiments included optimization of soaking time at maximum temperature, quantity of metallic precursor, and amount of sodium in terms of NaF layer thickness required for selenization. The absorber surface was coated with a 50 to 60 nm thick layer of CdS as hetero-junction partner by chemical bath deposition. A window bi-layer of i:ZnO/ZnO:Al was deposited by RF magnetron sputtering. The thickness of i:ZnO was increased to reduce the shunt resistance to improve open circuit voltage. The cells were completed by depositing a Cr/Ag front contact by thermal evaporation. Efficiencies greater than 13% was achieved on glass substrates. The performance of the cells was co-related with the material properties.
AdviserDhere, Neelkanth
PublisherUniversity of Central Florida
DegreePh.D.
Degree DisciplineDepartment of Mechanical, Materials and Aerospace Engineering
Degree GrantorEngineering and Computer Science
Degree ProgramMaterials Science and Engineering
Graduation Date2006-05-01
TypeDoctoral dissertation
Access LevelPublic - Allow Worldwide Access
Release Date2007-01-11
RepositoryUniversity Archives
Repository CollectionElectronic Theses and Dissertations
IdentifierCFE0001035
Access Linkhttp://purl.fcla.edu/fcla/etd/CFE0001035

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