Realization of 16.9% Efficiency on Nanowires Heterojunction Solar Cells with Dopant‐Free Contact for Bifacial Polarities

Abstract Low‐cost and efficient interfacial layer construction with the required charge selectivity and compatibility is necessary for nanostructured solar cells, and the proper integration of the interfacial layer with the light‐trapping system is required to improve the power conversion efficiency of the cell. Herein, low‐cost Si nanowires‐based solar cells with tunneling heterojunctions are developed by the deposition of MoO x and spin‐coating of Cs 2 CO 3 as the carrier‐selective layers. The power conversion efficiency of 16.9% for a device of 4 cm 2 in area is achieved by Si nanowires solar cells by the self‐assembly of ultra‐thin SiO x as the surface tunneling passivation layer. Self‐assembly is realized with an ultraviolet O 3 treatment process at room temperature. Quasi‐steady‐state photoconductance, microwave‐detected photoconductance decay, and constant current–voltage measurements are used to characterize the passivation quality and tunneling transportation properties of the ultra‐thin SiO x layers. Interfacial charge recombination is suppressed and effective carrier tunneling properties are developed by the growth of ≈1.5 nm thick SiO x layers on the surfaces of the Si nanowires. This proposed Si nanowires solar cell architecture featuring tunneling heterojunctions achieves high performance and may be suitable for fabricating industrialized Si nanowires‐based photovoltaic devices through a cost‐effective, simple, and low‐temperature process.