INVESTIGATION OF TRANSPORT AND OPTICAL PROPERTIES OF MESOPOROUS ANATASE AND RUTILE TiO2 FILMS FOR APPLICATION IN DYE-SENSITIZED SOLAR CELLS

The transport of electrons through TiO2 anatase and rutile thin films synthesized via sol-gel route has been investigated using electronic and optical spectroscopic studies. Mesoporosity of the films is confirmed by poroellipsometry. A smaller electron effective mass in anatase can be accounted for larger effective Bohr radius of trap electrons observed in anatase than in rutile. Further, the smaller effective mass in anatase favors high mobility. A mott transition is observed in anatase with change in temperature but not in rutile. Luminescence of self-trapped excitons is observed in anatase thin films, that implies a strong lattice relaxation.