All-solution-processed-inverted polymer solar cells on PET substrates with CuOx thin film as an anode interlayer

Low-cost solution process becomes the strategic principle for the fabrication of polymer solar cell. However, the cathode or anode interlayer are usually deposited by using vacuum evaporation due to the hydrophobicity problem and the temperature restriction of PET substrates. Here, we have successfully fabricated copper oxide (CuO_x) thin film as an anode interlayer in the inverted P3HT:PC₆₁BM solar cells on the PET substrates at low temperature via the sol-gel method. The CuO_x thin film can module the Schottky barrier and form an ohmic contact at the organic/metal interface, which make it a great hole transportation layer. In addition, we post- anneal the devices at 110°C to compensate the defect state at the organic/inorganic interface. Thus, the fill factor of the devices has been increased from 53.3% to 63.5% and the power conversion efficiency of devices has been improved from 3.04% to 3.95%.