Self-powered electrochromic device is a kind of instrument that can change transmittance with the electricity converting from solar energy. To realise the dual functions of solar energy harvesting and transmittance changing in one material, a novel derivative of triphenylamine (4-((4-(dimethylamino)phenyl)(phenyl)amino)benzyl)phosphoric acid (Ph₂ABPA-Me₂) is designed and synthesized in this paper. 1H NMR, FT-IR and MS were used to characterize the structure of the compound. Working electrode was made by dissolving the compound in chloroform and then immersing titanium dioxide-coated fluorine-doped tin oxide glass in the solution for 24 h. Its spectroelectrochemical properties were investigated with a UV-vis-IR spectrophotometer and a potentiostat, which allowed us to acquire transmittance spectra under potential control in a solution of 0.1 mol/L lithium perchlorate in propylene carbonate. The experiment was carried out with three electrodes system in which A wire acted as reference electrode and Pt wire as counter electrode. The working electrode shows light yellow with relatively high transmittance at -1.5 V and dark green with low transmittance at +2.5 V. The maximum transmittance contrast between the two states is 64.2% at 629 nm. Meanwhile, to investigate the photovoltaic properties of Ph₂ABPA-Me₂, Ph₂ABPA-Me₂-based electrochromic devices were made by sandwiching the working electrode and Pt-based counter electrode together with electrolyte of Iodolyte AN-50. The photovoltaic properties were measured with a solar simulator under 1 sun AM1.5G illumination. Energy conversion efficiency of 0.32% was obtained, with short-circuit current density of 1.32 mA/cm², open-circuit voltage of 0.44 V and fill factor of 0.54. All the results mentioned above suggest that the compound has dual functions of electrochromism and photovoltaics. Compared with traditional photoelectrochromic devices with both a photovoltaic electrode and an electrochromic electrode, the dual functional Ph₂ABPA-Me₂-based electrochromic device shows properties of simple construction, cheap to make and friendly to environment, and thus may have potential applications in buildings, vehicles and numerous types of displays.

Key words: triphenylamine derivative, photovoltaic, electrochromism, photoelectrochromic devices, self-powered device