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Download fileAnalysis and optimisation of the glass/TCO/MZO stack for thin film CdTe solar cells
journal contribution
posted on 2018-07-24, 08:24 authored by Francesco Bittau, C. Potamialis, Mustafa Togay, Ali AbbasAli Abbas, Patrick IsherwoodPatrick Isherwood, Jake BowersJake Bowers, Michael WallsMichael WallsMagnesium-doped Zinc Oxide (MZO) films have recently been proposed as a transparent buffer layer for thin film CdTe solar cells. In this study, the band gap of MZO buffer layers was tuned for CdTe solar cells by increasing the substrate
temperature during deposition. Films were deposited by radio-frequency magnetron sputtering. Devices incorporating an optimised MZO buffer layer deposited at 300 °C with a band gap of 3.70 eV yielded a mean efficiency of 12.5% and a highest efficiency of 13.3%. Transmission electron microscopy showed that MZO films are uniformly
deposited on the transparent conductive oxide (TCO) layer surface. The favourable band alignment seems to positively counterbalance the low doping level of the MZO layer and its high lattice mismatch with CdTe. Titanium-doped indium oxide, tin-doped indium oxide and aluminium-doped zinc oxide TCOs were also used as alternatives to
fluorine-doped tin oxide (FTO), in combination with MZO films. The use of titaniumdoped
indium oxide and tin-doped indium oxide TCOs did not improve the device efficiency achieved compared with FTO, however using aluminium-doped zinc oxide coupled with a boro-aluminosilicate glass substrate the mean and highest efficiencies
were further improved to 12.6% and 13.4% respectively.
Funding
The authors would like to thank support from the EPSRC for funding this research (EP/J017361/1 and EP/N026438/1).
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