Inverted polymer solar cells with a low-temperature ramp annealed sol–gel derived aluminum-doped ZnO nano-ridge film as a cathode buffer layer

The aluminum-doped zinc oxide (AZO) thin films with nano-ridge structures were fabricated via the low-temperature ramp annealed sol–gel derived process. The power conversion efficiency, especially the short circuit current density, was dramatically improved upon using the AZO nano-ridge structured thin films as the cathode buffer layers in inverted polymer solar cells (PSCs) with comparison to the intrinsic zinc oxide (i-ZnO) planar thin films. Furthermore, the thickness of AZO nano-ridge buffer layer can be enhanced significantly to about 120 nm without sacrificing the solar cell performance, which brings convenience to PSCs manufacturing by an industrial scale production.