Highly conductive bilayer transparent conducting oxide thin films for large-area organic photovoltaic cells

Highly conductive In-doped CdO/Sn-doped In₂O₃ (CIO/ITO) bilayer transparent conducting oxide (TCO) thin films were prepared by combining, in sequence, metal-organic chemical vapor deposition (MOCVD) and ion-assisted deposition (IAD) techniques. The bilayer substrates, with a low In content of ∼19 atom % and a low sheet resistance of only ∼4.9 ω/□, were investigated as anodes in the bulk-heterojunction (BHJ) organic photovoltaic (OPV) devices using poly(2-methoxy- 5-(3′,7′- dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO-PPV):[6,6]-phenyl C₆₁ butyric acid methyl ester (PCBM) as the active layer. The bilayer anode OPVs of the current laboratory size (∼0.06 cm²) exhibit performance comparable to those of commercial ITO-based control devices. The effect of TCO conductivity on OPV performance in larger area devices is analyzed through a simulation model. The results reveal significant advantages of using the highly conductive bilayer TCO anodes for large-area OPV cells.