A coaxial-type pulsed arc plasma doping process for the lithium-ion thin-film electrolyte application

Abstract

A combinatorial lithium-ion thin-film electrolyte deposition process that uses different types of arc plasma sources has been developed for thin-film inorganic complementary electrochromic devices (ECDs). With the coaxial-type pulsed arc plasma doping process, the lithium doping tantalum pentoxide (Ta2O5:Li) thin-film electrolyte doped with two different frequencies has been investigated. Although a lower ion conductivity of 9.30 × 10−9 S/cm has been obtained with the Ta2O5:Li doped with the arc discharge frequency of 1 Hz than the arc discharge frequency of 4 Hz, the ECD has demonstrated a better optical modulation (ΔT) of 58.25%. To analyze the detailed material characteristic, the ion mobility and concentration have also been extracted from the Li drift current by the current–voltage (I–V) measurement with the isothermal transient ionic current method. The optimal Ta2O5:Li doped with the arc discharge frequency of 1 Hz has demonstrated a higher ion mobility of 8.22 × 10−10 cm2/V s and a lower concentration of 7.07 × 1019 cm−3. As a result, the electrolyte with higher ion mobility and lower concentration is more important than the higher ion conductivity for ECD applications.