Vertically aligned nanocomposite films by self-assembled epitaxial nucleation for super-broadband transparent conductors

Designing super-broadband transparent conductors is challenging because of the exclusive nature of conductivity and infrared transmittance. Here, using a one-step process, we created vertically aligned nanocomposite conducting films with high transparency across a super-broad wavelength range. Vertically aligned transparent Ba₃V₂O₈ nanocolumns with lateral ~100-nm widths enable high transmittance (>50%, even at a 4-μm wavelength) for all incident light and outperform that of Sn-doped In₂O₃, while the conducting SrVO₃ matrix retains low resistivity (<0.56 mΩ cm at room temperature). A combined study of scanning transmission electron microscopy, scattering scanning near-field infrared microscopy, and X-ray diffraction revealed that spontaneous phase separation of Ba₃V₂O₈ nanocolumns in a SrVO₃ matrix film occurs via self-assembled epitaxial nucleation. Our vertically aligned nanocomposite films provide a fertile platform for next-generation optoelectronics.