Large-area Back Contact Electrodes for Perovskite Solar Cells using Nanosphere Lithographic Techniques

Hybrid metal-halide perovskite solar cells (PSC), developed on a lab scale, have been shown to exhibit high power conversion efficiency (PCE). Hence, developing these devices on an industrial scale is being pursued. Compared to planar devices, back-contact interdigitated electrode (BCIE) architectures have several potential benefits: low reflection and parasitic absorption in metal contacts, a large active area for light absorption, and higher PCE. In this paper, we have successfully fabricated large-area ( 2.25 cm2) nanopatterned ITO/TiO2/SiO2/Ni electrodes of feature size 350 nm using a self-assembled colloidal monolayer as a sacrificial template. The novelty of the design lies in the fact that the resolution of electrode spacing (350 nm) is one order lower than that of state-of-the-art BCIEs, making it comparable to the perovskite material's average diffusion length and thereby improving the PCE of the PSC. This kind of nanosphere-lithography-mediated fabrication of honeycomb back-contact electrodes with 100% device active area will lead to new opportunities related to large-area low-cost back-contact perovskite solar cells.