Graphene/PbS as a Novel Counter Electrode for Quantum Dot Sensitized Solar Cells

Abstract

PbS nanoparticles were in situ deposited on graphene sheets by a successive ionic liquid adsorption and reaction method to prepare a graphene/PbS composite counter electrode for CdS/CdSe quantum dot sensitized solar cells (QDSCs). Under 1 sun illumination, the cells with graphene/PbS counter electrodes (CEs) show a maximum energy conversion efficiency of 2.63%, which is remarkably higher than that of those employing PbS (1.28%) or graphene (0.23%) CEs. Electrochemical impedance spectroscopy analysis shows that graphene/PbS composite counter electrodes have lower charge-transfer resistance at the interface of the CE and the polysulfide redox electrolyte, compared to those cells with PbS and graphene counter electrodes. For the first reported CdS/CdSe-sensitized cells with the G/PbS CE, a cell performance with 2.63% efficiency (V oc = 559 mV, J sc = 11 mA/cm2, FF = 0.42) was obtained, which is comparable with the photovoltaic properties of the cells with optimized conventional Cu2S CEs (η = 3.01%, V oc = 564 mV, J sc = 11.6 mA/cm2, FF = 0.46). Our results indicate the potential application of graphene/noble metal sulfide composite electrodes in high-efficiency QDSCs.

Quasi Core/Shell Lead Sulfide/Graphene Quantum Dots for Bulk Heterojunction Solar Cells

“…Zhang et al 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 4 deposition method, and demonstrated their improved sensitivity to light upon deposition of PbS films with different thicknesses by electron beam thermal evaporation. Parand et al 34 employed PbS/G nanocomposites as a counter electrode in the CdS/CdSe QD sensitized solar cells, which were grown by in situ deposition of PbS QDs on graphene sheets using SILAR method.…”

Recent progress in the preparation and application of quantum dots/graphene composite materials

“…In 2014, Parand et al fabricated a GR/PbS composite as the counter electrode for CdS/CdSe QDs sensitized solar cells (QDSC). 85 The maximum conversion efficiency was 2.63%, which was much higher than that of the sole PbS (1.28%) or graphene (0.23%) counter electrode. It is suspected that the GR/ PbS electrode provides low charge-transfer resistance in order to enhance its conversion efficiency.…”

Graphene/CuS/PbS nanocomposite as an effective counter electrode for quantum dot sensitized solar cells

“…In order to make G/CuS/PbS CEs, graphene sheets were prepared from natural graphite powder by a modified Hummers' method as we described before [25].…”

“…However, the typical energy conversion efficiencies of QDSCs are still lower than dye sensitized solar cells (DSCs) which are mainly originated by the low fill factors in QDSCs. The fill factor in QDSCs is generally less than 0.6 (fill factors of 0.75 -0.8 is simply obtained in DSCs) which restricts the further efficiency enhancements [25,28]. According to the previous researches, reducing the series resistance of the CE and improving the charge transfer kinetics at the CE/electrolyte interface clearly improves the fill factor [29][30][31].…”