MATERIALS FOR SOLAR CELLS |
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SnO2 Buffer Layer with N Ions Implantation and Its Application in CdTe Solar Cells |
LIU Yuan, TANG Peng, ZHANG Jingquan, WU Lili, LI Wei, WANG Wenwu, FENG Lianghuan
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College of Materials Science and Engineering, Sichuan University, Chengdu 610065 |
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Abstract SnO2 thin films with thickness about 30 nm were prepared by RF magnetron sputtering and implanted with N ions by ion implantation technique, which were applied in CdTe solar cells as buffer layers. The results show that after N ions implantation, transmittance of SnO2 buffer layer is around 1—3 percentage points lower than FTO in 300—800 nm range, but sheet resistance is obviously increased, especially for sample with 10 min N ions implantation, of which surface morphology is cellular and shows many hollows, and the surface morphology of CdS layers has also changed. The results of Kelvin probe show that work function of SnO2 buffer layers increase with implantation time of N ions, whose maximum value is 5.075 eV and is 0.15 eV larger than intrinsic SnO2 buffer layer. The results of X-ray photoelectron spectroscopy show that after 10 min N ions implantation, the bind energy of N1s become lower than intrinsic SnO2 buffer layer, but both the bind enegy of O1s and the concentration of oxygen in non-stoichiometric oxides in the surface region are increased. The results of CdTe solar cells show that efficiency increases from 10.76% to 12.47% after N ions implantation, open circuit voltage increases from about 750 mV to above 790 mV, and the uniformity is also improved.
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Published: 10 September 2017
Online: 2018-05-07
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