Quantum Dot Solar Cells. Semiconductor Nanocrystals as Light Harvesters
18 Oct 2008-Journal of Physical Chemistry C (American Chemical Society)-Vol. 112, Iss: 48, pp 18737-18753
TL;DR: In this paper, three major ways to utilize semiconductor dots in solar cell include (i) metal−semiconductor or Schottky junction photovoltaic cell, (ii) polymer−smiconductor hybrid solar cell, and (iii) quantum dot sensitized solar cell.
Abstract: The emergence of semiconductor nanocrystals as the building blocks of nanotechnology has opened up new ways to utilize them in next generation solar cells. This paper focuses on the recent developments in the utilization of semiconductor quantum dots for light energy conversion. Three major ways to utilize semiconductor dots in solar cell include (i) metal−semiconductor or Schottky junction photovoltaic cell (ii) polymer−semiconductor hybrid solar cell, and (iii) quantum dot sensitized solar cell. Modulation of band energies through size control offers new ways to control photoresponse and photoconversion efficiency of the solar cell. Various strategies to maximize photoinduced charge separation and electron transfer processes for improving the overall efficiency of light energy conversion are discussed. Capture and transport of charge carriers within the semiconductor nanocrystal network to achieve efficient charge separation at the electrode surface remains a major challenge. Directing the future resear...
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TL;DR: This work reviews the historical development of Transition metal dichalcogenides, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.
Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.
13,348 citations
TL;DR: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency as mentioned in this paper, and many DSC research groups have been established around the world.
Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...
8,707 citations
TL;DR: Nanocrystals (NCs) discussed in this Review are tiny crystals of metals, semiconductors, and magnetic material consisting of hundreds to a few thousand atoms each that are among the hottest research topics of the last decades.
Abstract: Nanocrystals (NCs) discussed in this Review are tiny crystals of metals, semiconductors, and magnetic material consisting of hundreds to a few thousand atoms each. Their size ranges from 2-3 to about 20 nm. What is special about this size regime that placed NCs among the hottest research topics of the last decades? The quantum mechanical coupling * To whom correspondence should be addressed. E-mail: dvtalapin@uchicago.edu. † The University of Chicago. ‡ Argonne National Lab. Chem. Rev. 2010, 110, 389–458 389
3,720 citations
TL;DR: In this paper, the development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed.
Abstract: Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.
3,305 citations
TL;DR: In this paper, the authors discussed the steps that have led to this discovery, and the future of this rapidly advancing concept have been considered, and it is likely that the next few years of solar research will advance this technology to the very highest efficiencies while retaining the very lowest cost and embodied energy.
Abstract: Over the last 12 months, we have witnessed an unexpected breakthrough and rapid evolution in the field of emerging photovoltaics, with the realization of highly efficient solid-state hybrid solar cells based on organometal trihalide perovskite absorbers. In this Perspective, the steps that have led to this discovery are discussed, and the future of this rapidly advancing concept have been considered. It is likely that the next few years of solar research will advance this technology to the very highest efficiencies while retaining the very lowest cost and embodied energy. Provided that the stability of the perovskite-based technology can be proven, we will witness the emergence of a contender for ultimately low-cost solar power.
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TL;DR: In this paper, the authors examined the charge transfer between the various components of the hybrid solar cells and showed that a smaller volume fraction of nanorods and a larger volume of polymer can be used to conduct holes with higher mobilities.
Abstract: On account of their nano-scale size, large aspect ratio and high conductivity, single-walled carbon nanotubes (SWNTs) have emerged as an attractive choice for conducting composite materials. Composites incorporating SWNTs show percolation dominated conductivity with a much lower volume threshold (volume fraction ≈ 10), compared to those with nanoparticles. Two-thirds of SWNTs are p-type semiconductors with holes as the charge carriers. Using the holeblocking nature of SWNTs, conducting polymers having SWNTs as dopants are effectively used as the hole buffering and electron transport layers in organic light-emitted diodes (OLEDs). For the active layer of OLEDs and organic photovoltaic (OPV) devices, incorporation of SWNTs enhances the charge separation and facilitates charge transport, hence improving the performance, i.e., the short circuit current, the filling factor and power conversion efficiency. However, since SWNTs are a mixture of metallic and semiconducting nanotubes with a small bandgap (≈ 0.6 eV), both electrons and holes in the composite matrix prefer to transfer onto and then be quenched on the SWNTs. Directly incorporating SWNTs into active layers of OLEDs and OPV devices does not facilitate the electron/hole separation, nor does it improve the performances of devices. On the other hand, semiconductor nanoparticles, possessing large and tunable bandgaps (1–2 eV), can be incorporated into conducting polymers to form hybrid solar cells. Holes are transported along the polymer chains and electrons hop along the nanoparticle network. However, nanoparticles with large volume fractions are needed because of their high percolation threshold (>≈30%). By contrast, the volume fraction for the conducting polymer is small, leading to low hole mobility and hence limiting the solar cell efficiency. Semiconductor nanorod-polymer hybrid solar cells benefit from the quasi-one-dimensional (1-D) electron transport along the rods, a mechanism which allows the use of a smaller volume fraction of nanorods and a larger volume fraction of polymer to conduct holes with higher mobilities. Although Alivisatos et al. have demonstrated that longer nanorods lead to higher energy conversion efficiency, nanorods of larger lengths and uniformly distributed diameters are difficult to fabricate. Semiconductor nanoparticle-SWNT hybrids have been the subject of recent interest as a consequence of the development of methods for the chemical modification of SWNTs. Such hybrids are well suited for use in optoelectronic devices, given the tunable bandgap of nanoparticles, quasione-dimensional (1-D) transport of SWNTs, and the ease of chemical fabrication. As part of a drive towards finding applications, an examination of the charge transfer (CT) between the various components of the hybrids is needed. By using such hybrid materials as photo-electrodes, efficient electron transfer from semiconductor nanoparticles, such as CdS, CdSe, and CdTe (donor) to SWNTs (acceptor) has been demonstrated by several groups to lead to increased photon generated current (Fig. 1). The CT also results in photolumiC O M M U N IC A IO N
163 citations
Book•
01 Jan 1997
TL;DR: The mechanics of nanoscale suspensions (K.J. Nozik et al. as mentioned in this paper ) and charge transfer in nanoparticles (D.V. Kamat, D.F. Meisel).
Abstract: Introduction (P.V. Kamat, D. Meisel). Preparation and characterization of semiconductor nanoparticles (H. Weller, A. Eychmuller). The mechanics of nanoscale suspensions (K.T. Miller, C.F. Zukoski). Sonochemistry in colloidal systems (F. Grieser). Charge transfer in nanoparticles (D. Meisel). Spectroscopy of metal colloids -- some comparisons with semiconductor colloids (P. Mulvaney). Surface characterization of nanostructured systems (M. Tomkiewicz). Quantum well and superlattice electrodes (A.J. Nozik). Pseudopotential theory of nanometer silicon quantum dots (L.--W. Wang, A. Zunger). Luminescent porous silicon: synthesis, chemistry, and applications (M.J. Sailor, J.L. Heinrich, J.M. Lauerhaas). Composite semiconductor nanoclusters (P.V. Kamat). Photoelectron transfer in nanocomposite films, layer by layer self--assembled from polycations and anionic semiconductors (J.J. Fendler). Semiconductor nanocrystals in photoconductive polymers: charge generation and charge transport (Y. Wang). Nanostructure and size quantization in chemical solution deposited semiconductor films (S. Gorer, G. Hodes). Electrodeposition and characterization of nanocrystalline semiconductor films (K. Rajeshwar, N.R. de Tacconi). Nanocrystalline electronic junctions (M. Gratzel). Nanostructures in analytical chemistry (E. Pelizzetti, C. Minero). Semiconductor--mediated photocatalysis for organic synthesis (Y. Li, L. Wang). Application of nanoparticles in the photocatalytic degradation of water pollutants (N. Serpone, R.F. Khairutdinov). Applications in photocatalytic purification of air (X. Fu, W.A. Zeltner, M.A. Anderson). Author index. Subject index.
160 citations
TL;DR: Heat treatment is shown to be extremely useful for activating the CNT fiber surfaces for electron transfer and presents new opportunities for a wide range of electrochemical and analytical applications.
Abstract: Carbon nanotube (CNT) fibers have been used to fabricate microelectrodes with an attractive electrochemical behavior. By combining the advantages of CNT materials and fiber microelectrodes, the new material expands the scope of CNT-based electrochemical devices. The CNT fiber offers a marked decrease in the overvoltage for the NADH, dopamine, and hydrogen peroxide and circumvents NADH surface fouling effects. Heat treatment is shown to be extremely useful for activating the CNT fiber surfaces for electron transfer. SEM imaging and cyclic-voltammetric data indicate that the heat treatment leads to the removal of nonconducting residues and exposure of a “fresh” CNT surface. The new electrode material thus presents new opportunities for a wide range of electrochemical and analytical applications.
160 citations
TL;DR: The in situ mineralization of crystalline CdTe quantum dots on the surfaces of oxidized multiwalled carbon nanotubes (MWNTs) demonstrates a controlled synthetic route to the synthesis of complex nanoscale heterostructures.
Abstract: The generation of nanoscale interconnects and supramolecular, hierarchical assemblies enables the development of a number of novel nanoscale applications. A rational approach toward engineering a robust system is through chemical recognition. Here, we show the in situ mineralization of crystalline CdTe quantum dots on the surfaces of oxidized multiwalled carbon nanotubes (MWNTs). We coordinate metallic precursors of quantum dots directly onto nanotubes and then proceed with in situ growth. The resulting network of molecular-scale “fused” nanotube−nanocrystal heterojunctions demonstrates a controlled synthetic route to the synthesis of complex nanoscale heterostructures. Extensive characterization of these heterostructures has been performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV−visible spectroscopy, ...
155 citations
TL;DR: It is demonstrated that ac deposition voltage and time can control the CdS/TiO(2) composite architecture, which is crucial in determining the overall efficiency of the water-splitting reaction.
Abstract: A novel fabrication route for core/sheath heterostructure CdS/TiO2 nanotube arrays is proposed using ac electrodeposition for application in photoelectrochemical cells. The morphologies of the CdS/TiO2 electrodes, which were prepared by electrochemically depositing CdS directly into anodic titanium nanotubes from an electrolyte containing Cd2+ and S in dimethyl sulfoxide, were characterized by a field emission scanning electron microscope (FESEM). The deposited material was found to be in a hexagonal CdS structure by x-ray diffraction (XRD). The synthesized CdS/TiO2 electrodes showed much higher photocurrent density in the visible wavelength region than pure TiO2 nanotube arrays. We demonstrate that ac deposition voltage and time can control the CdS/TiO2 composite architecture, which is crucial in determining the overall efficiency of the water-splitting reaction. The maximum photocurrent density was obtained with the core/sheath heterostructure CdS/TiO2 nanotube arrays, which were fabricated by deposition of CdS at 5 V for 30 min with 2.5 µm tube length.
153 citations