A Low-Temperature Solution-Processed Nickel Oxide Nanoparticles and Phosphotungstic Acid Composite as an Anode Interface Layer for Organic Solar Cells

The anode interface layer (AIL) plays a crucial role in organic solar cells (OSCs). The typical PEDOT:PSS AIL generally requires annealing at temperatures over 150 °C and involves high material costs. Herein, we report a solution-processed inorganic composite AIL for OSCs by combining nickel oxide nanoparticles (NiOx NPs) and phosphotungstic acid (PWA). The NiOx NPs:PWA AIL is simply prepared by spin-coating their mixed solution and subsequent annealing at 100 °C. In contrast to NiOx NPs or PWA AIL, the NiOx NPs:PWA composite AIL exhibits a smoother interface and higher conductivity, which facilitates charge transfer to the anode. PM6:Y6 OSC with NiOx NPs:PWA AIL could achieve a higher power conversion efficiency (15.7%) than the sole NiOx NP OSC (9.9%) and sole PWA OSC (10.4%), which is comparable to the PEDOT:PSS device (15.5%). The estimated material cost of the NiOx NPs:PWA AIL is only ∼15% of the PEDOT:PSS cost. This work illustrates the potential of the NiOx NPs:PWA AIL for further applications in the commercial fabrication of OSCs.