Highly efficient electro-optic polymers through improved poling using a thin TiO₂-modified transparent electrode

A sol-gel derived thin titanium dioxide (TiO₂) layer was spin-coated onto indium-tin-oxide substrate to improve poling efficiency of recently developed electro-optic (E-O) polymers. The thin TiO₂ layer significantly blocks excessive charge injection and reduces the leakage current during high field poling. Ultralarge E-O coefficients, up to 160-350 pm/V at 1310 nm, have been achieved. These results show higher poling efficiency (enhancement of 26%-40%) compared to the results of poled films without the TiO₂ layer. This enhancement can be explained by field distribution flattening effect at high injection barrier with the insertion of TiO₂ barrier layer.