26.7% efficiency silicon heterojunction solar cells achieved by electrically optimized nanocrystalline-silicon hole contact layers

Abstract Thanks to the prominent passivating contact structures, silicon heterojunction (SHJ) solar cell has recently achieved revolutionary advancements in the photovoltaic industry. This is, however, bound to further strengthen its contact performance for gaining the competitive edge in the period of technology transformation. Here, we developed SHJ cells with improved rear contact consisting of a p-type doped nanocrystalline silicon and a tailored transparent conductive oxide. Benefiting from the low contact resistance of hole-selective contacts (< 5 mΩ·cm2), a high power conversion efficiency of 26.74% together with a record filling factor (FF) of 86.48% were certified on industrial-grade silicon wafers (274 cm2, M6 size). The electrical properties of the modified SHJ cells were thoroughly analyzed in comparison with the normal p-type transporting layer counterparts (i.e., amorphous silicon), and the improved charge carrier transport in behind were also fully demonstrated.