A Transparent to Dark Non-Complementary Electrochromic Device Based on Al~(3+) Guest Ions with TMTU/TMFDS~(2+) Redox Couple for Robust Stability

摘要

Al~(3+)-based electrochromic devices (ECDs) are expected to substitute Li+-based ECDs as the next-generation smart windows options. Compared to Li~+, Al~(3+) possess large quantities in the earth and safety, while the smaller ionic radius and three-electron redox mechanism can break the capacity bottleneck of inorganic electrochromic materials (ECM). However, limited by the strong electrostatic interaction between Al~(3+) with ECM and the lack of matching counter electrodes, the research on Al~(3+) is still focused on three-electrode system without applications in ECDs. Different from conventional complementary structure, the ECM/redox/CCE (catalytic counter electrode) structure is introduced to enhance the kinetics (from 1.56 × 10~(?11) to 9.45 × 10~(?11) cm~2 s~(?1)) of the Al~(3+) intercalation/ extraction process. Based on this structure, Al~(3+)-based ECDs achieve a series of excellent properties: a) almost total absorption of visible and near-infrared waveband (T_(500-1500) nm ≈0%) under ?1.0 V; b) ultra-low driving voltage (53% transmittance modulation under ?0.1 V); c) excellent memory effect with the presence of redox couple; d) wide range of color modulation capability (yellow, green, blue, and black); e) outstanding energy efficiency. Moreover, the possibility of Na+ as an alternative to Li+ is also verified and Na~+-based ECDs exhibit comparable electrochromic properties to Li~+-based ECDs.