Sean Lim

Hydrogen molybdenum bronzes for hole transport layers on crystalline silicon solar cells

The stoichiometry of molybdenum oxide (MoOJ films needs to be controlled to ensure effective hole transport layers. If the layer is too metallic (x = 2) or too insulating (x = 3) then the layers transport and passivation properties can be impacted. We report on a method of forming MoOx films on crystalline silicon wafer surfaces by spin-coating hydrogen molybdenum bronze solutions. It is shown that an ∼ 2 nm thick interfacial SiOx layer forms under the spin-coated MoOx films and that the MoOx as deposited is amorphous and sub-stoichiometric. Thermal annealing in air reduces the concentration of oxygen vacancies in the MoOx with stoichiometric films being achieved by annealing at 400 °C. The decay of minority carrier lifetime measurements with time demonstrates the importance of capping the films before measurements for reliable results.