We report a novel approach to the instantaneous photoinitiated synthesis of mixed anatase-rutile nanocrystalline TiO2 thin films with a three-dimensional nanostructure through pulsed white light irradiation of photosensitive Ti-organic precursor films. Pulsed photoinitiated pyrolysis accompanied by instantaneous self-assembly and crystallization occurred to form graphitic oxides-coated TiO2 nanograins. Subsequent pulsed light irradiation working as in situ pulsed photothermal treatment improved the crystalline quality of TiO2 film despite its low attenuation of light. The non-radiative recombination of photogenerated electrons and holes in TiO2 nanograins, coupled with inefficient heat dissipation due to low thermal conductivity, produces enough heat to provide the thermodynamic driving force for improving the crystalline quality. The graphitic oxides were reduced by pulsed photothermal treatment and can be completely removed by oxygen plasma cleaning. This photoinitiated nanofabrication technology opens a promising way for the low-cost and high-throughput manufacturing of nanostructured metal oxides as well as TiO2 nanocrystalline thin films.

High-energy flash cure lamps process thick film materials (<10 um) over large areas (<100 cm2) within milliseconds and are capable to deliver higher energy and power densities (20 J/cm2 and 20 kW/cm2) allowing for a more complete curing and elimination of flaws that would exist in conventional treatment. Click reactions are especially attractive for patterned devices as they have minimal shape change during curing and have a more predictable structure compared to free radical acrylate polymerization. Pentaerythritol tetrakis(3-mercaptopropionate) and 2,4,6-Triallyloxy-1,3,5-triazine were combined at 3:4 by weight and then spin coated on copper foil substrates. The solutions were processed both thermally and with exposure to a xenon flash bulb. Thermal treatment consisted of heating the sample at 80°C on a hot plate over night. Flash curing was accomplished using a Novacentrix Pulseforge 1300 system. The flash lamp curing fluence and intensities were varied to determine their effects on degree of cross-linking, dielectric constant, breakdown field and energy storage. The degree of cross-linking was determined through comparative FTIR studies. Dielectric constant was measured using an Agilent 4294a impedance analyzer from 100 Hz-100 MHz with a two terminal setup. Breakdown strength and energy density measurements were taken using Radiant Technology's Precision Ferroelectric tester with a 10 kV source. The printed films averaged 1-3 microns thick as observed by an SEM cross section measurement. It was found that dielectric constant varies with both treatment intensity and fluence. Energy densities were calculated using the ideal capacitor equation and ranged from 1.5-4.8 J/cm3.