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Cadmium Sulfide Thickness Reduction in CIGS Solar Cells by Application of ALD-Zinc Magnesium Oxide
D. Bagrowski, S. Spiering, T. Schnabel, J.-P. Becker
CIGS, Thin Film Solar Cell, ALD, Buffer, ZnMgO
Perovskites and Other Non-Silicon Materials and Devices, Multijunctions/Tandems
Subtopic: CI(G)S, CdTe and Related Thin Films
Event: 38th European Photovoltaic Solar Energy Conference and Exhibition
Session: 3BV.2.13
462 - 466
ISBN: 3-936338-78-7
Paper DOI: 10.4229/EUPVSEC20212021-3BV.2.13
0,00 EUR
Document(s): paper, poster


We investigated the potential of reducing the thickness of solution grown CdS buffer in Cu(In,Ga)Se2–based solar cells by substitution of the adjacent radio frequency sputtered i-ZnO high resistive layer with an atomic layer deposited Zn1-xMgxO layer. Typically, the standard CdS thickness is about 50 nm combined with a 50-80 nm sputtered i-ZnO layer. Former investigations showed a significant decrease of the device performance by reducing the CdS thickness below 30 nm. We deposited the Zn1-xMgxO layer in a standard thermal as well as in a plasma-assisted mode. We compared both processes by varying the Zn/Mg-pulse ratios and the layer thicknesses. We realized best results with a reduced CdS thickness down to 5 nm when combined with 10-30 nm Zn1-xMgxO with 0.15 ≤ x ≤ 0.3 without efficiency loss compared to reference cell with standard CdS thickness. The cells showed no or very low cold light soak (CLS) effect. A maximum cell efficiency of 18.5 % (VOC = 727 mV, FF = 78.0 %, JSC = 32.7 mA/cm², 10 min CLS) could be achieved comparable to reference cells of 18.6 % efficiency (VOC = 741 mV, FF = 79.9 %, JSC = 31.4 mA/cm²).