Highly conductive PdCoO2 ultrathin films for transparent electrodes

TL;DR

This paper demonstrates the successful synthesis of highly conductive, transparent PdCoO2 ultrathin films with potential applications in transparent electrodes, combining high electrical conductivity and optical transparency.

Contribution

The study reports a novel synthesis method for PdCoO2 ultrathin films with record-high conductivity and transparency, advancing transparent electrode technology.

Findings

Sheet conductance up to 5.5 mS in films thicker than 2.1 nm

High conductivity exceeding 10^4 S/cm at critical thickness

High optical transmittance in the near-infrared region

Abstract

We report on the successful synthesis of highly conductive PdCoO2 ultrathin films on Al2O3 (0001) by pulsed laser deposition. The thin films grow along the c-axis of the layered delafossite structure of PdCoO2, corresponding to the alternating stacking of conductive Pd layers and CoO2 octahedra. The thickness-dependent transport measurement reveals that each Pd layer has a homogeneous sheet conductance as high as 5.5 mS in the samples thicker than the critical thickness of 2.1 nm. Even at the critical thickness, high conductivity exceeding 104 Scm-1 is achieved. Optical transmittance spectra exhibit high optical transparency of PdCoO2 thin films particularly in the near-infrared region. The concomitant high values of electrical conductivity and optical transmittance make PdCoO2 ultrathin films as promising transparent electrodes for triangular-lattice-based materials.