Zinc Molybdate-carbon Composites as Counter Electrode Materials for Dye-sensitized Solar Cells

doi:10.15541/jim20140156

Abstract

Abstract:

Sheet-like structured zinc molybdate (ZnMoO₄) was firstly synthesized by hydrothermal method. Then, graphite (G) and conductive carbon (Cc) modified ZnMoO₄ (denoted as ZnMoO₄-G and ZnMoO₄-Cc) were fabricated by dispersing ZnMoO₄ into graphite (G) and conductive carbon (Cc) solutions, respectively. The obtained ZnMoO₄-G and ZnMoO₄-Cc composites were used as electrocatalysts for dye-sensitized solar cells (DSCs), exhibiting promising potential as counter electrode materials. The experimental results demonstrated that the DSC assembled with sole ZnMoO₄ showed an overall light conversion efficiency of 4.19%, while the DSCs made of ZnMoO₄-G and ZnMoO₄-Cc counter electrodes displayed power conversion efficiencies of 6.56% and 7.36%, respectively. The solar cell performance obtained by ZnMoO₄-Cc counter electrode was comparable to Pt-based DSCs (7.81%). Various characterization techniques, such as electrochemical impedance spectra (EIS), cyclic voltammetry (CV) and Tafel polarization curve, were employed to evaluate the electrocatalytic activity of all investigated materials. Among all investigated counter electrodes, the high solar cell performance obtained by ZnMoO₄-Cc counter electrode could be attributed to superior electrical conductivity of conductive carbon material and excellent electrocatalytic activity of sheet-like structured ZnMoO₄-Cc.

Key words: dye-sensitized solar cell, hydrothermal synthesis, ZnMoO4, photovoltaic performance, electric catalytic

CLC Number:

O643

TANG Bei-Bei, GUO Ming-Xing, JIANG Wei, YIN Shu-Hui, ZHANG Man-Xia, WANG Liang, ZHANG Yi-Ming, ZHENG Lei, MENG Yue-Qi. Zinc Molybdate-carbon Composites as Counter Electrode Materials for Dye-sensitized Solar Cells[J]. Journal of Inorganic Materials, 2014, 29(11): 1133-1138.

Figures/Tables 8

Fig. 1 SEM images of ZnMoO4

Fig. 2 XRD patterns and photo (inset) of ZnMoO4 powders

Fig. 3 Photocurrent-voltage curves of DSCs using different materials as counter electrodes

Fig. 4 Nyquist plots of the dummy cell fabricated with two identical electrode for different counter electrodes

Table 1 Photovoltaic performance of DSCs with different counter electrodes and EIS parameters of the dummy cell assembled with two identical counter electrodes

Sample	V_oc/V	J_sc/(mA·cm^-2)	FF	η/%	R_s/(Ω·cm²)	R_ct/(Ω·cm²)	Z_N/(Ω·cm²)	E_pp/V
ZnMoO₄	0.64	13.20	0.50	4.19	15.77	2.85	6.31	0.361
ZnMoO₄-G	0.67	16.58	0.59	6.56	15.20	1.99	4.67	0.138
ZnMoO₄-Cc	0.70	16.79	0.63	7.36	13.32	1.46	1.89	0.124
Pt	0.73	18.94	0.55	7.81	8.66	0.96	0.19	0.120

Fig. 5 SEM images of (a) ZnMoO4, (b) ZnMoO4-G and (c) ZnMoO4-Cc

Fig. 6 Cyclic voltammograms of different CEs

Fig. 7 Tafel curves of the dummy cell fabricated with two identical electrode for different counter electrodes

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