Gradient Al-doped ZnO multi-buffer layers: Effect on the photovoltaic properties of organic solar cells

摘要

In this work, gradient Al-doped ZnO multi-buffer layers (MBLs) were used as the electron transport layers (ETLs) of organic solar cells (OSCs) for the first time. Three kinds of MBLs were prepared using a facile sol-gel process and deposited on a homo-buffer layer (ZnO). Compared to a device based on a multi-ZnO buffer layer, devices with the gradient-doped MBL displayed enhanced power conversion efficiency from 2.11% to 3.43%, which were caused by the efficient light transmission and charge carrier transport, derived from the higher film qualities, denser and more uniform surface morphologies, and improved conductivities of the gradient-doped MBLs. Results indicated that a device with ZnO/MBL (0.5:1.0 at%(Al/Zn)) simultaneously enhanced the short-circuit current and fill factor. This study presents an innovative and effective method for improving the quality of ETLs for efficient OSCs. (C) 2015 Elsevier B.V. All rights reserved.