An Electrochromic Nickel Phosphate Film for Large-Area Smart Window with Ultra-Large Optical Modulation

Transition metal phosphates were first developed for the electrochromic application. The obtained NiHPO 4 ·3H 2 O film achieves an ultra-large optical modulation of 90.8%, and the electrochromic mechanism is systematically elucidated using in situ and ex situ techniques. A large-area electrochromic smart window with 100 cm 2 is constructed, which displays superior performances in regulating natural lighting and storing electrical charges.