Effect of the Ag deposition rate on the properties of conductive transparent MoO3/Ag/MoO3 multilayers

The properties of molybdenum trioxide (20 nm)/silver (x nm)/molybdenum trioxide (35 nm) multilayer structures, deposited by simple vacuum evaporation, depend significantly on the deposition rate and on the thickness of the silver layer. If the presence of a commutation from an insulating state to a highly conductive state in these structures is usual, we show that, the thickness of the layer of Ag corresponding to the percolation of the metal paths, decreases from 8 nm to 4 nm when the Ag deposition rate increases from 0.2 nm/s to 0.4 nm/s. The transmission being optimum at 10-11 nm, the calculation of the factor of merit shows that the best structures are obtained for silver films approx. 10 nm thick deposited at a rate between 0.3 nm/s and 0.4 nm/s. When the optimal structures MoO3/Ag/MoO3 are used as anode in planar organic solar cells anode/Cul/CuPc/C-60/Alq3/Al they allow achieving power conversion efficiency of the same order of magnitude than that achieved by reference cells using ITO as anode. (C) 2013 Elsevier B.V. All rights reserved.