Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (11): 2632-2640.doi: 10.3866/PKU.WHXB201207301

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Photoelectric Conversion Efficiency of N719/TiO2-Inx%/FTO Film Electrodes Incorporating In Doped at the TiO2 Surface

CHENG Hui1,2, YAO Jiang-Hong1,2, CAO Ya-An1,2   

  1. 1. College of Physics, Nankai University, Tianjin 300071, P. R. China;
    2. The Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda Applied Physics School, Nankai University, Tianjin 300457, P. R. China
  • Received:2012-06-07 Revised:2012-07-23 Published:2012-10-17
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (50872056, 51072082, 21173121).


Nanoparticles of TiO2 with surface modification by In doping were prepared using a sol-gel technique. These materials had the general formula TiO2-Inx%, where x represents the mole percent of In3+ ions in the combined In3+ and Ti4+ metal ion content. N719/TiO2/FTO (fluorine doped tin oxide) and N719/ TiO2-Inx%/FTO film electrodes were prepared, using N719 dye as a sensitizing agent. These thin film electrodes were incorporated into solar cells composed of 0.5 mol·L-1 LiI, 0.05 mol·L-1 I2, methoxypropionitrile (MPN) and Pt. It was determined that the photoelectric conversion efficiencies of the N719/TiO2-Inx%/FTO film electrodes were higher than that of N719/TiO2/FTO. In particular, the conversion efficiency of N719/TiO2-In0.1%/FTO was 20% greater than that of N719/TiO2/FTO. The band structure and In3+ ion content of TiO2-Inx% samples were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and optical diffuse-reflection spectroscopy (DRS), as well as by examination of photoluminescence (PL) and surface photocurrent action spectra. The photo-induced charge transfer processes of the N719/TiO2-Inx%/FTO film electrodes were also elucidated using surface photocurrent action spectra. The results showed that O-In-Cln (where n=1 or 2) species were formed at the TiO2 surface, with surface state energy levels 0.3 eV below the conduction band of TiO2. The surface state energy levels of these species effectively inhibit the recombination of photo-generated carriers during the photocurrent generation process, and also serve to increase the anodic photocurrent and significantly improve the photoelectric conversion efficiency of N719/TiO2-Inx%/FTO thin film electrodes. This work also discusses the interfacial light-induced charge transfer mechanisms in these materials.

Key words: TiO2-Inx%, O-In-Cln (n=1, 2) species, Surface-sensitization, N719/TiO2-Inx%/FTO, Photoelectric conversion efficiency