An electrochromic phosphorescent iridium(III) complex for information recording, encryption, and decryption

Electrical stimuli-induced change in absorption spectra, or electrochromism, has been well studied due to its promising applications in displays, sensors, smart windows, memory chips, and electronic papers, etc. However, electrochromic luminescent materials are rather scarce. In view of their advantages including easy tuning of luminescence color, short response time, and relatively high contrast, an electrochromic phosphorescent Ir(III) complex (Ir-OH) with an O-H moiety in the N^N ligand is designed. This complex displays long-lived phosphorescence, whose wavelength and lifetime are very sensitive to complex concentration, pH value, and electric field. Based on the interesting electrochromic phosphorescence of complex Ir-OH, a quasi-solid information recording and storage device has been designed. A short-lived fluorescent dye has been selected to encrypt the recorded information. In view of the much longer lifetime of Ir-OH compared with that of the fluorescent dye, decryption has been accomplished by using time-resolved imaging techniques. Hence, it is believed that electrochromic phosphorescence will open up a new and efficient avenue for applications in information encryption and decryption. A novel protonable phosphorescent Ir(III) complex that is responsive to concentration, pH value, and electric field, is designed and synthesized. Based on the interesting electrochromic phosphorescence behavior, an information recording and storage device is fabricated, and information protection can be achieved via fluorescence lifetime imaging and time-gated luminescence imaging techniques.