Organic polymer solar cell using low-temperature deposited AZO/Ag/AZO transparent electrodes

The electrical, optical, and structural properties of indium-free Al-doped ZnO (AZO)/Ag/AZO triple-layer electrodes deposited by room temperature sputtering without post treatments were investigated. The conductivity of the AZO/Ag/AZO triple-layer electrodes grown on glass substrates can be improved by the insertion of an Ag layer. The best figure of merit value (Φ_TC) was 39.9×10^-3Ω^-1for the AZO/Ag/AZO electrodes with 8 nm-thick Ag layer. Moreover, bulk hetero junction organic polymer solar cells based on the AZO/Ag/AZO triple-layer and AZO single-layer electrodes were fabricated for a comparative study. The polymer solar cells using AZO/Ag/AZO transparent electrodes exhibited higher performance than the cell using pure AZO electrodes, due to much lower sheet resistance of the electrode. This implies that indium-free AZO/Ag/AZO triple-layer electrodes are an appropriate transparent electrode for low-cost and low-temperature processing organic photovoltaics.