All-inorganic flexible epitaxial SrNbO3/mica thin films with ultrahigh figure of merit as indium-free transparent conductors

Abstract

Nowadays, flexible transparent conductors (TCs) have been widely applied for solar cells, stretchable integrated circuits, sensor networks, and human-machine interaction devices. Recently, nondoped correlated metallic oxides (CMOs) have aroused great interest as indium-free TCs. In this work, an all-inorganic flexible CMO thin film with an ultrahigh figure of merit (FOM) value was fabricated using a simple preparation technology: the direct deposition of epitaxial SrNbO3 thin films on a stratiform mica substrate via a pulsed laser deposition (PLD) process. From the measured optical transmittance (Tr) spectra in conjunction with the ellipsometic data, it is found that SrNbO3 film possesses a superior visible light transparency compared with commonly investigated SrVO3 due to its larger bandgap. The charge transport measurements indicate that the dc electrical conductivity (σ) of SrNbO3 is higher than that of SrVO3, attributed presumably to a weaker electron correlation and therefore a smaller effective electron mass (m*) in SrNbO3. Bending cyclic tests reveals high mechanical durability and bending stability in SrNbO3 films. This detailed investigation demonstrates a great potential of the all-inorganic flexible epitaxial SrNbO3/mica film as an indium-free TC with high performance for future optoelectronic applications.