Enhanced electrochromic performance on anodic nickel oxide inorganic device via lithium and aluminum co-doping

Anodic materials like nickel oxide play a very important role in lithium-ion battery, solar cells and especially electrochromic devices (ECDs). While the optical modulation and cycle stability performance of nickel oxide (NiO_x) for electrochromic devices still require improvement. Here, lithium-doping (LiNiO_x) and lithium-aluminum co-doping nickel oxide (Al-LiNiO_x) thin films are prepared through co-sputtering. Compared with the un-doped nickel oxide films, the optical modulation and cycle stability of the nickel oxide film containing both lithium and aluminum were significantly improved. LiNiO_x films show improvement in the transmittance contrast while the transmittance of bleached state decreases. Al-LiNiO_x films not only increase optical modulation, but also improve the transmittance of bleached state. Furthermore, ITO/WO₃/LiNbO₃/Al-LiNiO_x/ITO inorganic all-solid-state ECD with good performance was prepared. The transmittance of the ECD in the bleached state reaches 74.5% at 550 nm, the transmittance contrast could be 44%, and the stability of ECD is good. These indicate that lithium-aluminum co-doping could be a good way to improve electrochromic performance.