Effective Passivation of Nanostructured TiO2 Interfaces with PEG-Based Oligomeric Coadsorbents To Improve the Performance of Dye-Sensitized Solar Cells

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• 作者：Yong-Gun Lee ; Suil Park ; Woohyung Cho ; Taewook Son ; P. Sudhagar ; June Hyuk Jung ; Sanghyuk Wooh ; Kookheon Char ; Yong Soo Kang
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：March 22, 2012
• 年：2012
• 卷：116
• 期：11
• 页码：6770-6777
• 全文大小：465K
• 年卷期：v.116,no.11(March 22, 2012)
• ISSN：1932-7455

文摘

A novel poly(ethylene glycol) (PEG) based oligomeric coadsorbent was employed to passivate TiO₂ photoanodes resulting in the large increase in both open-circuit voltage (V_oc) and short-circuit current density (J_sc) primarily because of the reduced electron recombination by the effective coverage of vacant sites as well as the negative band-edge shift of TiO₂. The effective suppression of electron recombination was evidenced by electrochemical impedance spectroscopy (EIS) and by stepped light-induced transient measurements of photocurrent and voltage (SLIM-PCV). The work function measurements also showed that the existence of coadsorbents on TiO₂ interfaces is capable of shifting the band-edge of TiO₂ photoanodes upwardly resulting in the increase in photovoltage. In addition, the coadsorbent was proven to be effective even in the presence of common additives such as LiI, 4-tert-butylpyridine, and guanidinium thiocyanate. The effect of Li⁺ cation trapping by ethylene oxide units of the coadsorbent was particularly notable to significantly increase V_oc at a small expense of J_sc. Consequently, the introduction of novel PEG-based oligomeric coadsorbents for TiO₂ photoanodes is quite effective in the improvement of photovoltaic performance because of the simultaneous increase in both V_oc and J_sc.