Abstract
Ag2S quantum dots were deposited on the surface of TiO2 nanorod arrays by a two-step photodeposition. The prepared TiO2 nanorod arrays as well as the Ag2S deposited electrodes were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, suggesting a large coverage of Ag2S quantum dots on the ordered TiO2 nanorod arrays. UV–vis absorption spectra of Ag2S deposited electrodes show a broad absorption range of the visible light. The quantum dot-sensitized solar cells (QDSSCs) based on these electrodes were fabricated, and the photoelectrochemical properties were examined. A high photocurrent density of 10.25 mA/cm2 with a conversion efficiency of 0.98% at AM 1.5 solar light of 100 mW/cm2 was obtained with an optimal photodeposition time. The performance of the QDSSC at different incident light intensities was also investigated. The results display a better performance at a lower incident light level with a conversion efficiency of 1.25% at 47 mW/cm2.
Highlights
Quantum dot-sensitized solar cells (QDSSCs) have attracted increasing attention due to their relatively low cost and potentials to construct high-efficiency energy conversion systems [1]
Morphology of the TiO2 nanorod array (NRA) Figure 2 shows the field emission scanning electron microscopy (FESEM) images of TiO2 NRA grown on the fluorine-doped SnO2-coated conducting glass (FTO) substrate (FTO/TiO2) viewed from top (a) and cross-section (b)
The compact layer may reduce the recombination of electron from the FTO to the electrolyte in the working course of QDSSCs by segregating them
Summary
Quantum dot-sensitized solar cells (QDSSCs) have attracted increasing attention due to their relatively low cost and potentials to construct high-efficiency energy conversion systems [1]. Compared with organic dyes used in dye-sensitized solar cells (DSSCs), semiconductor sensitizers in the form of quantum dots (QDs) present higher extinction coefficients and adjustable absorption spectra by controlling their size [2,3]. The deposition of QD sensitizers on the electron acceptor (e.g., TiO2) related to the loading amount and the connection between QDs and electron acceptor plays a key role in the QDSSC performance. QDs with various sizes should be deposited on the surface of mesoporous TiO2 separately as a requirement for efficient charge separation [6]. The coverage of mesoporous TiO2 by QDs is much less than a full monolayer [6,7], which leads to insufficient light harvesting and back electron transfer from exposed TiO2 to
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