Abstract: A tunnel-junction,comprising n⁺ and p⁺ layers,was inserted into the a-Si:H/μc-Si:H tandem cells with an interlayer structure to improve the carrier transport efficiency.The influence of the properties of tunnel-junction,including the microstructures,dopant-content and thickness of n⁺/p⁺ layers,on the performance of the tandem cells was experimentally investigated for optimization of the tunnel-junction synthesis.The preliminary results show that the insertion of an optimized tunnel-junction matters.To be specific,the tunnel-junction increased the initial conversion efficiency up to 12.20%,decreased the light degradation rate down to 9%,and improved the light-soaking stability of the tandem cells,because of the enhancement of carrier transport efficiency and because of the alleviation of short-circuit current-density mismatching of sub-cells.Possible mechanisms responsible for enhancement of carrier transport efficiency were also tentatively discussed in a thought provoking way.