Methyl- and fluoro-substituted triphenylamine core toward fast-switching visible and near-infrared electrochromic polymers

Herein, two monomers MTPA and FTPA, and their corresponding polymers (PMTPA and PFTPA) based on a methyl-and fluoro-substituted triphenylamine were synthesized by Stille reaction and electropolymerization. MTPA exhibited the red-shift absorption and fluorescence emission spectra, and lower E_onset (0.53 V) compared with FTPA (0.57 V), which is beneficial to achieve high-quality polymers. The polymer films exhibited reversible color transition from yellow green to deep blue for PMPTA and from dark brown to light blue for PFTPA, respectively. In addition, both PMTPA and PFTPA films exhibited good optical contrasts of 36 % and 40 % at 1100 nm, respectively. The coloration efficiency and response times at 1100 nm are 196.4 C⁻¹ cm² with 0.6 s for PMTPA, and 160.9 C⁻¹ cm² with 1.4 s for PFTPA, respectively. These polymer films demonstrated excellent electrochemical property and electrochromic performance. These results will also provide a new strategy to rationally design the excellent electrochromic polymers based on the triphenylamine core.