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Interface passivation effects on the photovoltaic performance of quantum dot sensitized inverse opal TiO2 solar cells
Author(s)
Hori, Kanae
Zhang, Yaohong
Tusamalee, Pimsiri
Nakazawa, Naoki
Yoshihara, Yasuha
Wang, Ruixiang
Toyoda, Taro
Hayase, Shuzi
Shen, Qing
Date Issued
July 1, 2018
Type
Article
Abstract
Quantum dot (QD)-sensitized solar cells (QDSSCs) are expected to achieve higher energy conversion efficiency than traditional single-junction silicon solar cells due to the unique properties of QDs. An inverse opal (IO)-TiO2 (IO-TiO2) electrode is useful for QDSSCs because of its three-dimensional (3D) periodic nanostructures and better electrolyte penetration compared to the normal nanoparticles (NPs)-TiO2 (NPs-TiO2) electrode. We find that the open-circuit voltages Voc of the QDSSCs with IO-TiO2 electrodes are higher than those of QDSSCs with NPs-TiO2 electrodes. One important strategy for enhancing photovoltaic conversion efficiency of QDSSCs with IO-TiO2 electrodes is surface passivation of photoanodes using wide-bandgap semiconducting materials. In this study, we have proposed surface passivation on IO-TiO2 with ZnS coating before QD deposition. The efficiency of QDSSCs with IO-TiO2 electrodes is largely improved (from 0.74% to 1.33%) because of the enhancements of Voc (from 0.65 V to 0.74 V) and fill factor (FF) (from 0.37 to 0.63). This result indicates that ZnS passivation can reduce the interfacial recombination at the IO-TiO2/QDs and IO-TiO2/electrolyte interfaces, for which two possible explanations can be considered. One is the decrease of recombination at IO-TiO2/electrolyte interfaces, and the other one is the reduction of the back-electron injection from the TiO2 electrode to QDs. All of the above results are effective for improving the photovoltaic properties of QDSSCs.
Citation
Nanomaterials, 8(7), 2018