THE THERMOCHROMIC BEHAVIOR OF CYANINE DYES DOPED IN SILICA PHASES PREPARED BY LIQUID-PHASE-DEPOSITION METHOD

The method of liquid phase deposition (LPD) has an interesting feature that some kinds of organic compounds can be directly doped into silic a layers. We doped a cyanine dye o-5-(1-ethyl-2(1H)-quinolylidene)-1,3 -pentadienyl] quinolinium bromide) in silica thin films by using the L PD method and observed thermochromic behavior of the prepared samples. The samples are colorless just after preparation. When they are maint ained at a raised temperature, they turn blue. The origin of this ther mochromic behavior has been attributed to the elimination of water mol ecules out of silica phases. A semi-empirical MO calculations also sup port the proposed mechanism.