Perovskite/c-Si TandemSolar Cells with High Temperature Carrier-Selective Passivating Contacts

Abstract

Due to increasing population growth and industrialization, the energy demand is soaring around the world. In order to meet this energy demand and continuing with business as usual, there is an increased need for fossil fuels. Burning of fossil fuels such as coal, gas and oil lead to emission of carbon dioxide in atmosphere. Emission of carbon dioxide rises the earth’s surface temperature and is leading to global warming. In order to tackle this crisis, an alternative to fossil fuels need to be investigated. In this regard, renewable energy sources are key as they can be replenished. Solar energy is one of the fastest growing and promising renewable energy sources.

Photovoltaics (PV) modules or solar panels have been installed across the world, converting solar energy into electrical energy. The PV market is dominated by single junction crystalline silicon (c-Si) solar cells. In order to improve the efficiency of single junction solar cells beyond their efficiency limit, tandemsolar cells, which stack one solar cell on top of another, are being actively explored by researchers. In this work, we have focused on perovskite/c-Si tandem solar cells.

Since direct contact of metal with semiconductor leads to recombination, the concept of carrier-selective passivating contacts (CSPCs), which separates the absorber from the metal by a thin passivating layer, becomes important. The most common type of CSPCs are doped hydrogenated amorphous silicon (a-Si:H) on intrinsic amorphous silicon, as in the case of silicon heterojunction (SHJ) solar cells. The other type of CSPCs are polycrystalline silicon (poly-Si) on ultrathin silicon oxide (SiOx) as in the case of poly-Si solar cells. Depending on the fabrication temperature of CSPCs, the former comes under low temperature CSPCs while the latter is a type of high temperature CSPCs. While low temperature CSPCs have been successfully integrated in perovskite/c-Si tandem solar cells, research involving high temperature CSPCs is less developed. In this work, high temperature CSPCs are studied, optimized and integrated in perovskite/c-Si tandem solar cells. In addition, the performance of tandem solar cells is evaluated not only in terms of efficiency but also energy yield which is more relevant for outdoor environment. In addition to poly-Si, this work explores novel materials such as polycrystalline silicon oxide (poly-SiOx) and polycrystalline silicon carbide (poly- SiCx) as high temperature CSPCs...