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Evaluation of Limiting Factors Affecting Photovoltaic Performance of Low‐Temperature‐Processed TiO 2 Films in Dye‐Sensitized Solar Cells
Author(s) -
Lee TaekYong,
Kim HuiSeon,
Park NamGyu
Publication year - 2014
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201301043
Subject(s) - photocurrent , materials science , dye sensitized solar cell , energy conversion efficiency , diffusion , analytical chemistry (journal) , dielectric spectroscopy , photoconductivity , chemical engineering , optoelectronics , electrochemistry , electrode , chemistry , electrolyte , organic chemistry , physics , engineering , thermodynamics
Limiting factors affecting photovoltaic performance of dye‐sensitized solar cell employing low‐temperature‐processed TiO 2 films were investigated. TiO 2 films were prepared at a low temperature of 200 °C using the normal alcohol‐containing binder‐free TiO 2 paste (LT200). Their photovoltaic performance was compared to a high‐temperature (550 °C) annealed TiO 2 film prepared using a polymer binder containing TiO 2 paste (HT550). Compared to the proportional increase in conversion efficiency with TiO 2 film thickness upto 14 μm for HT550, the increase in efficiency was terminated at relatively smaller thickness of about 8 μm for LT200 mainly due to unaugmented photocurrent. From the transient photocurrent–voltage studies, the electron transport rate was found to be almost identical, while charge recombination was one order of magnitude faster for LT200. Consequently, the electron diffusion length was more than 2–3 times shorter for LT200 than for HT550. Electron diffusion length and electron life time obtained from electrochemical impedance analysis were well consistent with those observed from transient measurement. Density of states (DOS) was evaluated to be shallow and narrow in LT200, which was responsible for limiting photovoltaic performance in the low‐temperature processed TiO 2 film.