Tuning oxygen vacancies in vanadium-doped molybdenum oxide for silicon solar cells with hole selective contact

Abstract

Near stoichiometric molybdenum oxide (MoO3-x) film has attracted extensive interest as superior hole-selecting material in optoelectronic devices. However, the existence of multi-oxidation states significantly affects its work function and carrier transport behaviors. In this work, we have proposed a facile way to modulate the oxidation states of solution-processed MoO3-x with vanadium ions (V5+) doping (MoO3-x:V), beneficial for improved hole-selecting contact performance with silicon. As the doping concentration of V5+ increases, oxygen vacancies and reduced Mo5+ ions reduce, resulting in the increase of work function of MoO3-x film. The effective carrier lifetime of MoO3-x deposited Czochralski silicon has been largely improved from 60.1 to 153.0 μs (Δn = 1015 cm−3) at the optimized doping concentration of 5%, and the contact resistivity is reduced from 9.1 to 2.1 Ω cm2 simultaneously. The finished solar cells with the scheme of Ag/MoO3-x:V/n-Si have exhibited significantly improved conversion efficiency. Our results have demonstrated a very promising way to modulate the stoichiometry and work function of MoO3-x film, which has great potential in solar cell and light emitting diode applications.