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Model for electronic transport in Cu(In,Ga)Se 2 solar cells
Author(s) -
Niemegeers A.,
Burgelman M.,
Herberholz R.,
Rau U.,
Hariskos D.,
Schock H.W.
Publication year - 1998
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/(sici)1099-159x(199811/12)6:6<407::aid-pip230>3.0.co;2-u
Subject(s) - heterojunction , acceptor , voltage drop , materials science , optoelectronics , conduction band , voltage , chalcopyrite , layer (electronics) , dipole , copper indium gallium selenide solar cells , drop (telecommunication) , condensed matter physics , solar cell , chemistry , copper , nanotechnology , electron , electrical engineering , physics , engineering , organic chemistry , quantum mechanics , metallurgy
Temperature‐dependent measurements of the current–voltage characteristics and of the junction admittance of ZnO/CdS/Cu(In,Ga)Se 2 heterojunction solar cells are presented, together with numerical modelling of these experimental results. We explain the cross‐over between dark and illuminated current–voltage characteristics currently observed for this type of device by the impact of the defect chalcopyrite layer at the surface of the Cu(In,Ga)Se 2 absorber. Our model assumes an illumination‐dependent voltage drop across a defect layer with a thickness of 15 nm to explain the cross‐over. The voltage drop results from the electrical dipole made up of donor‐like states at the interface between the defect layer and CdS and deep acceptor states in the defect layer itself. The illumination dependence of this voltage drop is explained by photogenerated holes trapped by the deep acceptor states in the defect layer. Numerical simulations have been carried out using the program SCAPS‐1D in order to verify our model assumptions. From our model, indirect conclusions are derived concerning the maximum conduction band offsets between CdS and the defect layer and between CdS and ZnO. Copyright © 1998 John Wiley & Sons, Ltd.