Zirconium-Doped Zinc Oxide Nanoparticles as Cathode Interfacial Layers for Efficiently Rigid and Flexible Organic Solar Cells

Low-temperature zinc oxide nanoparticles (ZnO NPs) are widely applied as cathode interfacial layers (CILs) for rigid and flexible organic solar cells. However, the inferior optoelectronic properties of ZnO NPs constrain the improvement in the photovoltaic performance and enhance the thickness sensitivity. Herein, upon application of this ZnO:Zr NP as a CIL for inverted device construction, the maximum power conversion efficiency (PCEmax) is increased to 17.7%, with an enhancement of 12.0% compared to that of the pristine ZnO-based devices (15.8%). A series of optoelectronic characterizations have revealed that the Zr doping methodology would enhance the charge generation and extraction process and suppress trap-assisted recombination, which is beneficial for the synergistic improvement of the thickness tolerance and shelf stability. Encouragingly, ZnO:Zr NPs can be easily fabricated through a doctor-blade coating technique with remarkable performance (16.6%). More critically, this approach can be applied to the development of high-performance flexible solar cells, with a superb PCE of 16.0%.