The effect of ITO/Mo/MoO3 anode multilayer film on efficient hole extraction in MEH–PPV/ZnO NP hybrid solar cells

Acidic PEDOT:PSS anode buffer layers (ABLs) are widely used for improving efficiency in organic-based solar cells. Recently stable P-type metal oxides, such as NiO, MoO3, and V2O5, have been applied for replacing the commonly used acidic PEDOT:PSS ABL because of the difficulty in coating PEDOT:PSS solutions onto electrodes or polymer active layers. This highlights the importance of the fabrication and characterization of various ABLs that affect the efficiency of hole extraction and the blocking of electron backflows. We studied MoO3 ABLs formed by the rapid thermal annealing (RTA) of molybdenum (Mo) in oxygen atmosphere. In particular, we propose the use of an indium tin oxide (ITO)/Mo/MoO3 anode multilayer for efficient hole extraction in bulk heterojunction (BHJ)-structure organic-based solar cells. The formation of Mo and MoO3 thin films was controlled by the RTA time with a fixed annealing temperature of 350 °C. We obtained a two-fold improvement in the short circuit current (Jsc) of the device with the ITO/Mo/MoO3 anode multilayer film (AMF), compared to a device with a PEDOT:PSS ABL.