Sol–gel processed CuOx thin film as an anode interlayer for inverted polymer solar cells

We have used sol–gel derived copper oxide (CuO x ) thin film as an interlayer at the organic/metal interface to improve the performance of the inverted P3HT:PC 61 BM solar cells. The resulting interlayer can form an ohmic contact between the P3HT:PC 61 BM and electrode. Due to the formation of the ohmic contact, the series resistance of device has been decreased from 2.77 to 1.29 (Ω/cm 2 ). Simultaneously, the CuO x interlayer can redistribute the light intensity to enhance light absorption and thereby increases the current density form 11.0 to 11.9 (mA/cm 2 ). Thus, the power conversion efficiency (PCE) is improved from 3.11% to 4.02%.