High-performance orthorhombic correlated transparent conducting epilayer integrated on a flexible mica substrate: The case of CaMoO3

Abstract

Recently, cubic perovskite SrTMO3 (TM = V, Nb, and Mo) compounds have attracted great interest as correlated transparent conducting oxides (CTCOs). However, in theory, none of these three oxides is capable of completely covering the entire visible (Vis) light wavelength range with transparency. Herein, epitaxial orthorhombic CaMoO3 thin films were grown on flexible mica substrates using a pulsed laser deposition (PLD) method. By exploiting the tilting of MoO6 octahedra, an optimal balance between plasma energy (ћωp) and electrical conductivity (σ) was realized in CaMoO3. Electronic transport characterizations indicated that the σ value of CaMoO3 is comparable to that of SrTMO3. The optical transmittance spectra demonstrated that the CaMoO3 film possesses superior Vis transparency compared to SrTMO3. From the ellipsometry analysis, it was found that the O 2p – V 3d interband transition occurs at around 4.16 eV while the screened plasma energy (ћωp) is approximately 1.37 eV. The favorable absorption edges for both the long and short wavelength regions ensure the high transparency of CaMoO3 across the entire Vis spectrum. Additionally, bending cyclic tests illustrated the excellent mechanical durability and endurance of the CaMoO3/mica films. The present work is instructive for exploring alternative CTCOs beyond SrTMO3, demonstrating that the optimal balance between ћωp and σ can be realized by manipulating the TMO6 octahedral tilting to improve the transparent conducting performance of correlated perovskite-type oxides.