Modification of electron states in CdTe absorber due to a buffer layer in CdTe/CdS solar cells

Journal Article · Wed Oct 28 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4934680· OSTI ID:22492878

Major, J. D.; Pressman, A.; Phillips, L. J.; Durose, K. ^[1]

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1. Stephenson Institute for Renewable Energy and Department of Physics, School of Physical Sciences, Chadwick Building, University of Liverpool, Liverpool L69 7ZF (United Kingdom)

By application of the ac admittance spectroscopy method, the defect state energy distributions were determined in CdTe incorporated in thin film solar cell structures concluded on ZnO, ZnSe, and ZnS buffer layers. Together with the Mott-Schottky analysis, the results revealed a strong modification of the defect density of states and the concentration of the uncompensated acceptors as influenced by the choice of the buffer layer. In the solar cells formed on ZnSe and ZnS, the Fermi level and the energy position of the dominant deep trap levels were observed to shift closer to the midgap of CdTe, suggesting the mid-gap states may act as recombination centers and impact the open-circuit voltage and the fill factor of the solar cells. For the deeper states, the broadening parameter was observed to increase, indicating fluctuations of the charge on a microscopic scale. Such changes can be attributed to the grain-boundary strain and the modification of the charge trapped at the grain-boundary interface states in polycrystalline CdTe.

• OSTI ID: 22492878
• Journal Information: Journal of Applied Physics, Vol. 118, Issue 16; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BUFFERS
CADMIUM SULFIDES
CADMIUM TELLURIDES
DENSITY OF STATES
FERMI LEVEL
FILL FACTORS
GRAIN BOUNDARIES
LAYERS
POLYCRYSTALS
RECOMBINATION
SOLAR CELLS
SPECTROSCOPY
STRAINS
THIN FILMS
TRAPPING
ZINC OXIDES
ZINC SELENIDES
ZINC SULFIDES