Influence of Quantum Dot Concentration on Carrier Transport in ZnO:TiO₂ Nano-Hybrid Photoanodes for Quantum Dot-Sensitized Solar Cells.

Francis Maloney,Uma Poudyal,Wenyong Wang,Weimin Chen

doi:10.3390/nano6110191

Francis Maloney, Uma Poudyal + Show 2 more

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https://doi.org/10.3390/nano6110191

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Journal: Nanomaterials	Publication Date: Oct 25, 2016
Citations: 6	License type: CC BY 4.0

Affiliation: University of Wyoming

Abstract

Zinc oxide nanowire and titanium dioxide nanoparticle (ZnO:TiO2 NW/NP) hybrid films were utilized as the photoanode layer in quantum dot-sensitized solar cells (QDSSCs). CdSe quantum dots (QDs) with a ZnS passivation layer were deposited on the ZnO:TiO2 NW/NP layer as a photosensitizer by successive ion layer adsorption and reaction (SILAR). Cells were fabricated using a solid-state polymer electrolyte and intensity-modulated photovoltage and photocurrent spectroscopy (IMVS/PS) was carried out to study the electron transport properties of the cell. Increasing the SILAR coating number enhanced the total charge collection efficiency of the cell. The electron transport time constant and diffusion length were found to decrease as more QD layers were added.

Highlights

Since the development of the dye-sensitized solar cells (DSSCs) in 1991 [1], both dye-sensitized and quantum dot sensitized solar cells (QDSSCs) have attracted enormous attention in alternative energy research in both academic and industrial laboratories
Inorganic Quantum dots (QDs) represent the next-generation of solar cell sensitizers and have demonstrated many advantages over dyes including a size-dependent band-gap tunable to the infrared (IR) range, high stability and resistance to oxidation, possibilities for multi-layering of materials, an ability to generate multiple excitons, and the many permutations of materials that can comprise them. [4,5] QDs can be grown directly onto a photoanode using a variety of techniques
CdSe quantum dots were deposited on the zsitnucdoixeidde cNhWarsgfuesetrdawnistphoTritO2inNPQsDasStShCe pshtohtoaatnuodtielilzaeyerthineDzSiSnCcst[i1t6a]n. ium oxide (ZnO):TiO2 anode layer by a successive ionic layer adsorption and reaction (SILAR) method. 0.03 M Cd(NO3)2

Summary

Introduction

Since the development of the dye-sensitized solar cells (DSSCs) in 1991 [1], both dye-sensitized and quantum dot sensitized solar cells (QDSSCs) have attracted enormous attention in alternative energy research in both academic and industrial laboratories. To convert sunlight into energy, sensitized solar cells make use of a semiconducting photoanode coated with a light absorbing layer. Upon absorption, this sensitizing layer will generate an exciton (electron-hole pair), leading to the injection of an electron to the photoanode, and a hole to the electrolyte. SILAR deposition has several advantages over these previous methods in that it allows easy control over the size and density of the QDs, since the dot synthesis takes place during the cycling. It is relatively fast (the longest of depositions in this study lasting on the order of hours). SILAR is considered the best method for depositing multilayers over QD cores by alternating the injection of cationic and anionic precursors [5]

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