Research On Optoelectronic Properties And Application Of TiO₂/PbO Composite Materials

TiO₂ has been extensively investigated for various potential applications including photocatalytic water splitting, environmental remediation and third generation solar cells because of its good photoelectric properties. A series of studies suggest that the visible light absorption can be improved by the oxide semiconductor. This paper intends to enhance the photoconductivity of TiO₂ and supplement the study of photoconductivity about TiO₂ by compositing。TiO₂ and PbTiO₃ thin films were prepared by sol-gel process. By studying the influence of different polarization directions on lead titanate thin film and its composite material, it shows that the unpolarized film photocurrent density is ?j=0.8 μA/cm², the negative polarized film photocurrent density is ?j=1.2 μA/cm², the positive polarized film photocurrent density is ?j=0.7 μA/cm².TiO₂/ PbTiO₃ photocurrent density ?j=8μA/cm², PbO/PbTiO₃ photocurrent density ?j=18 μA/cm². The formation of heterojunction promotes the separation of electron holes and leads to improved optical current density. Different direction of residual polarization field has an important effect on the photocurrent density. Negative polarization field promoting electron hole separation made the photocurrent density improved, on the contrary, positive polarization field suppress electron hole separation. A positive or negative residual polarization field would reduce the photocurrent density whether TiO₂/ PbTiO₃ or PbO/ PbTiO₃. Interface barrier would suppress carrier transmission which leads to reduce photocurrent density.Different spin coating times has a significant influence on the microstructure and the photocurrent density of PbO/TiO₂. It shows that the magnitude of the photocurrent density increase first and then decrease. The maximum photocurrent density（?j=50μA/cm²）is obtained when coated 5 times, the minimum photocurrent density（?j=20 μA/cm²） under 6 times. There are two influencing factors on the photocurrent density: first, the PbO crystalline grain gradually grows up with the increased of coating times; second, not enough heterojunction formed at the interface between lead oxide and titanium oxide because of less spin coating times.