Improved diffusion and storage of lithium ions via recrystallization induced conducting pathways in a Li:Ta2O5-based electrolyte for all-solid-state electrochromic devices with enhanced performance

Chun-Chu Lin; Po-Hsun Chen; Min-Chen Chen; Min-Chuan Wang; Chih-Cheng Yang; Hui-Chun Huang; Chung-Wei Wu; Sheng-Yao Chou; Tsung-Ming Tsai; Ting-Chang Chang

doi:10.1088/1361-6528/ac5ca8

Improved diffusion and storage of lithium ions via recrystallization induced conducting pathways in a Li:Ta₂O₅-based electrolyte for all-solid-state electrochromic devices with enhanced performance

Nanotechnology. 2022 Apr 20;33(27). doi: 10.1088/1361-6528/ac5ca8.

Authors

Affiliations

¹ Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, R. O. C.
² Department of Applied Science, R.O.C. Naval Academy, Kaohsiung 813, Taiwan, R. O. C.
³ Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, R. O. C.
⁴ Department of Physics Division, Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan 325, Taiwan, R. O. C.
⁵ Department of Physics, and also with the Center of Crystal Research, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan.

PMID: 35272278
DOI: 10.1088/1361-6528/ac5ca8

Abstract

In this study, we have investigated the improvements in the performance of an all-solid-state complementary electrochromic device (ECD) by using the proposed high pressure treatment (HPT). The Li:Ta₂O₅electrolyte layer was recrystallized by the HPT utilizing pressurized CO₂gas (∼200 atm) and at low temperature (<60 °C), which enhanced the coloration performance of the WO₃/Li:Ta₂O₅/NiO complementary ECD by ∼20%. The reliability and durability of the ECD were confirmed by long term transmittance retention measurements, which indicated an improvement in the coloration performance by ∼14% upon the release of the bias voltages. The ability of the devices that were fabricated with and without the HPT process to withstand high temperature environments was also verified. In addition, photoluminescence (PL) and transmittance measurements were carried out to examine the effects of the bonding between WO₃and NiO. To determine the differences in lithium-ion (Li⁺) injection, electrical measurements were performed by utilizing varying pulse rising speeds to confirm device characteristics. The materials were characterized in terms of their composition and structure using high-resolution transmission electron microscopy along with energy-dispersive x-ray spectroscopy. Finally, a mechanistic model has been proposed to explain the improved EC characteristics based on the amorphous to crystalline transition accompanying the HPT process.

Keywords: electrochromic device (ECD); lithium ion; tantalum oxide; tungsten oxide.