Investigating the MgAl-Doping n-Type ZnO(MgAlZnO) Metal Oxide Film Used as the ITO Cathode Buffer Layer in the Inverted Polymer Solar Cell

n-Type ZnO obtained by Magnesium-Aluminum(Mg-Al) doping is reported in this paper. Mg-Al-doped ZnO (MgAlZnO) have been deposited on ITO substrates by spin-coat. The process of synthesizing n-type MgAlZnO film is performed in air. MgAlZnO film has grown with the substrate temperature 290°C. The amorphous MgAl-doping ZnO thin film is synthesized by sol-gel processing method. The UV-visible absorption of the Mg-Al doping ZnO thin film is carried out to investigate the optical property. By the doping a nearly 10% molecular fraction of Magnesium element(Mg) ,the UV-visible absorption curves of the Mg-Al co-doping ZnO is obviously blueshifted relative to the pristine ZnO. So, the Mg element broaden the its bandgap and improve the transparency of the MgAl-doping ZnO .The highly conductive transparent MgAl-doping ZnO film is obtained by the doping processsing. In this paper, the MgAl-doping ZnO metal oxide used as the cathode ITO buffer layer for the inverted polymer solar cell is also investigated. The PCE is greatly improved from 2.07% to 8.91% by the usage of the MgAl-doping ZnO metal oxide as the interface material. As for the loss of the open-circuit voltage relative to the conventional device structure with the PEDOT:PSS as the anode buffer layer, we discuss the possible underlying reasons. At last, we investigate the effect of the film morphology of MgAlZnO on the stability of the polymer solar cell.