A Low-Cost Polytetrafluoroethylene-Framed TiO2Electrode Decorated with Oleic Acid-Capped CdSe Quantum Dots for Solar Cell

Delele Worku Ayele,Bing-Joe Hwang,Wein-Nien Su

doi:10.1155/2013/394512

Delele Worku Ayele, Bing-Joe Hwang + Show 1 more

Open Access

https://doi.org/10.1155/2013/394512

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Abstract

Colloidal CdSe QDs have been assembled, as quantum dot-sensitized solar cells (QDSSCs), on a novel architecture comprising a polytetrafluoroethylene- (PTFE-) framed TiO2electrode for the first time. CdSe QDs are anchored on the surface of the film using a linker molecule (3-mercaptopropionic acid, MPA). The resulting photoelectrode comprises a TiO2compact layer and a PTFE-framed structural layer with average respective thicknesses of 2 μm for the compact layer and either 23 μm or 28 μm for the PTFE-framed structural layer. UV-vis absorption spectra show that more CdSe quantum dots are anchored on the surface of the modified with MPA TiO2film compared to direct absorption onto an unmodified film. Energy conversion efficiencies of up to 0.18% can be achieved with cells prepared from a TiO2(25 μm)/MPA/CdSe QD electrode. Electrochemical impedance measurements show that the recombination resistance is relatively higher for a cell assembled with TiO2(25 μm)/MPA/CdSe QD photoanode than with TiO2(25 μm)/CdSe QD resulting in an increase of cell efficiency. The PTFE-framed structure along with the compact layer is a new approach to QDSSC application that provides a tunable film thickness and a cost-effective preparation technique for the large-scale production of the photoanode.

Highlights

Dye-sensitized solar cells (DSSCs) have attracted much attention as a promising alternative energy source to conventional solid-state junction solar cells due to their low cost, low impact on the environment, and high efficiency [1]
We demonstrated a new type of photoanode composed of compact and structural layers for quantum dot-sensitized solar cells (QDSSCs) applications
The compact layer was made of a pure TiO2 paste, while the structural layer was prepared with PTFE to form a PTFE

Summary

Introduction

Dye-sensitized solar cells (DSSCs) have attracted much attention as a promising alternative energy source to conventional solid-state junction solar cells due to their low cost, low impact on the environment, and high efficiency [1]. Inorganic semiconductor quantum dots (QDs), such as CdS and CdSe, have been employed as sensitizers, mainly due to their specific advantages over conventional dyes [6,7,8,9]; for instance, the size quantization effect allows tuning of the band energy and visible response by varying the QD size [10, 11] Another advantage is that these QDs open new ways to utilize hot electrons or generate multiple charge carriers with one single photon through the impact ionization effect [12, 13]. The nanoporous nature of the TiO2 layer provides a high surface area that is of great importance to the efficient photon-to-electricity conversion because it first enhances QD loading and solar light absorption [26] It provides abundant TiO2 surface sites (direct route) and bare FTO conducting sites (indirect route), where the photoinjected electrons may recombine with species of electrolyte [27]. Polysulfide electrolyte was used as the redox couple to regenerate the photoexcited holes in the QDs with Pt being used as a counter electrode

Experimental

Results and Discussion

Conclusion