Optical, electrical, and structural properties of ZrON/Ag/ZrON multilayer transparent conductor for organic photovoltaics application

• We investigated ZrON/Ag/ZrON multilayer electrodes for use in organic photovoltaics.
• Transmission window region becomes wider with increasing ZrON layer thickness.
• ZrON/Ag/ZrON multilayer is more chemically stable than ITO/Ag/ITO multilayer.
• Solar cells with ZrON/Ag/ZrON show short circuit current comparable to ones with ITO.

We investigated the electrical and optical properties of chemically stable nitride-based ZrON/Ag/ZrON multilayers for use in organic photovoltaics. As the ZrON layer thickness increases, the carrier concentration smoothly decreases and the transmission window region becomes wider and gradually shifts toward the lower energy-side. The optical bandgap also decreases with decreasing carrier concentration. The ZrON/Ag/ZrON samples exhibit somewhat lower transmittance in the region of ∼400–800 nm than the ITO/Ag/ITO samples. The aging test shows that the resistivity of the ZrON/Ag/ZrON samples remains almost the same even after aging for 1 month in air. It is shown that the ZrON/Ag interface is more chemically stable than the ITO/Ag interface. Simulation results exhibit that the ZnPc:C60 bulk hetero-junction organic solar cells fabricated with the ZrON(30 nm)/Ag/ZrON(70 nm) layers give a short circuit current of 9.54 mA/cm2, which is comparable to that (10.54 mA/cm2) of the cells with 90-nm-thick ITO electrodes. The ZrON/Ag/ZrON samples experienced a large shift in the absorption edge. This behavior is explained in terms of the material characteristics of the ZrON layers and the higher refractive index of the ZrON/Ag/ZrON samples.