Transparent conducting oxide interlayer-free perovskite/c-Si tandem solar cells

Abstract

To solve the issues on environmental pollution and depletion of fossil fuels, research for high-efficiency solar cells has been attracted much attention. A tandem solar cell is being considered as a promising device architecture because it is capable of absorbing light in a wide wavelength range by stacking semiconductor materials having different bandgaps. For developing a tandem structure, it is essential to add an interlayer in which photo-induced electrons and holes recombine at the interface of different semiconductor materials. The interlayer should have excellent electrical conductivity for efficient carrier recombination and high transmittance to allow lots of light to reach the lower light absorption layer, simultaneously. Among various materials, Indium tin oxide (ITO) is commonly used as a conventional interlayer. However, the performance of the ITO layer is restricted due to its parasitic light absorption. Hence, it is necessary to develop a material that can replace ITO for the interlayer. In this study, by controlling the temperature condition of the doping process in forming a P-N junction on the front side of the crystalline silicon, a heavily doped emitter of crystalline silicon solar cell having high electrical conductivity was realized and the emitter layer was applied as the interlayer of the perovskite/c-Si tandem solar cell. As a result, the fabricated perovskite/c-Si tandem solar cell exhibited a power conversion efficiency of over 20% with a high filling factor of 82%, which implies that the heavily doped emitter layer would be a very efficient interlayer of tandem structure.