Enhanced photovoltaic and carrier collection efficiency of dye sensitized solar cell: Nb₂O₅ coated TiO₂ photoanode

ABSTRACT

Dye sensitized solar cells (DSSCs) were fabricated using Nb₂O₅ energy barrier layer is coated on the TiO₂ photoanode. This energy barrier (Nb₂O₅ layer) reduces the recombination rate of the photoinjected electrons with their counter holes. A monoclinic Nb₂O₅ energy barrier layer can be coated 1 and 3 times on a TiO₂ photoanode using a dip-coating method. The Nb₂O₅/TiO₂ photoanode exhibits enhanced photovoltaic performance, which is better than the bare TiO₂ photoanode. The results presented in this study show that this Nb₂O₅ layer forms an inherent energy barrier at the electrode-electrolyte interface. The electron transport and charge recombination behaviors of DSSCs were investigated by electrochemical impedance spectra (EIS) and the results illustrated that the DSSCs showed the lowest charge transport resistance and the longest electron lifetime. The electron transport and recombination were studied by stepped light- induced transient measurements of photocurrent and voltage (SLIM-PCV) method and shown that the electron diffusion length is increasing with the Nb₂O₅ coating.

KEYWORDS:

• Nb₂O₅
• Photoanode
• Electron transport

Acknowledgments

This work was supported by the 2013 Yeungnam University Research Grant, and also supported by “Human Resources Program in Energy Technology” of the Korea Institute of Energy Technology Evaluation and planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea. (No. 20154030200760).