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: In this paper, the authors combined CdS semiconductor quantum dots and single-crystalline rutile TiO2 nanorod arrays to produce a practical quantum dot sensitized solar cell.
81 citations
TL;DR: Traditional Pt counter electrode in quantum-dot-sensitized solar cells suffers from a low electrocatalytic activity and instability due to irreversible surface adsorption of sulfur species incurred while regenerating polysulfide (S(n)(2-)/S(2-)) electrolytes, so chemically synthesized Cu(2)ZnSn(S(1-x)Se(x))(4) nanocrystals were evaluated as an alternative to Pt.
Abstract: Traditional Pt counter electrode in quantum-dot-sensitized solar cells suffers from a low electrocatalytic activity and instability due to irreversible surface adsorption of sulfur species incurred while regenerating polysulfide (Sn2–/S2–) electrolytes. To overcome such constraints, chemically synthesized Cu2ZnSn(S1–xSex)4 nanocrystals were evaluated as an alternative to Pt. The resulting chalcogenides exhibited remarkable electrocatalytic activities for reduction of polysulfide (Sn2-) to sulfide (S2–), which were dictated by the ratios of S/Se. In this study, a quantum dot sensitized solar cell constructed with Cu2ZnSn(S0.5Se0.5)4 as a counter electrode showed the highest energy conversion efficiency of 3.01%, which was even higher than that using Pt (1.24%). The compositional variations in between Cu2ZnSnS4 (x = 0) and Cu2ZnSnSe4 (x = 1) revealed that the solar cell performances were closely related to a difference in electrocatalytic activities for polysulfide reduction governed by the S/Se ratios.
81 citations
TL;DR: In this article, shape-controlled and scalable synthesis of phase-pure pyrite (FeS2) nanocrystals employing the simple, inexpensive, thermal reaction of iron-oleylamine complexes with sulfur in oleylamine was reported.
Abstract: Nanocrystals from non-toxic, earth abundant materials have recently received great interest for their potential large-scale application in photovoltaics and photocatalysis. Here, we report for the first time on the shape-controlled and scalable synthesis of phase-pure pyrite (FeS2) nanocrystals employing the simple, inexpensive, thermal reaction of iron–oleylamine complexes with sulfur in oleylamine. Either dendritic nanocrystals (nanodendrites) or nanocubes are obtained by adjusting the iron-oleylamine concentration and thereby controlling the nucleus concentration and kinetics of the nanocrystal growth. Pyrite nanodendrites are reversibly assembled by washing with toluene and redispersed by adding the ligand oleylamine. The assembly–redispersion-process is accompanied by an increased absorption in the red/near-infrared spectral region for the aggregated state. This increased low-energy absorption is due to interactions between the closed-packed nanocrystals. High-concentration nanodendrite dispersions are used to prepare pyrite thin films with strong broadband extinction in the visible and near-infrared. These films are attractive candidates for light harvesting in all inorganic solar cells based on earth abundant, non-toxic materials as well as for photocatalytic applications.
80 citations
TL;DR: In this paper, high density and vertical ZnO/CdS core-shell nanorod arrays have been prepared directly on FTO substrates via a two-step electrochemical deposition process.
80 citations
TL;DR: In this paper, a mini-review of semiconductor photocatalysis is presented with the aim of enumerating underlying critical factors such as visible light harvesting, charge carrier separation, conduction and their utilization that determine the quantum efficiency.
Abstract: Hydrogen production from water and sunlight through photocatalysis could become one of the channels, in the not-so-distant future, to meet a part of ever growing energy demands. However, accomplishing solar water splitting through semiconductor particulate photocatalysis seems to be the ‘Holy Grail’ problem of science. In the present mini-review, some of the critical strategies of semiconductor photocatalysis are focused with the aim of enumerating underlying critical factors such as visible light harvesting, charge carrier separation, conduction and their utilization that determine the quantum efficiency. We attempted to bring out the essential requirements expected in a material for facile water splitting by explaining important and new designs contributed in the last decade. The newly emerged designs in semiconductor architecture employing nanoscience towards meeting the critical factors of facile photocatalysis are elucidated. The importance of band gap engineering is emphasized to utilize potential wide band gap semiconductors. Assistance of metal nanostructures and quantum dots to semiconductors attains vital importance as they are exuberant visible light harvesters and charge carrier amplifiers. Benevolent use of quantum dots in solar water splitting and photoelectrochemical water splitting provides scope to revolutionize the quantum efficiency by its multiple exciton generation features. A list of drawbacks and issues that hamper the much needed breakthrough in photocatalysis of water splitting is provided to invite attention to address them and move towards sustainable water splitting.
80 citations
References
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TL;DR: In this paper, the carrier collection efficiency and energy conversion efficiency of polymer photovoltaic cells were improved by blending of the semiconducting polymer with C60 or its functionalized derivatives.
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TL;DR: In this paper, the authors describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment.
Abstract: The optical properties of metal nanoparticles have long been of interest in physical chemistry, starting with Faraday's investigations of colloidal gold in the middle 1800s. More recently, new lithographic techniques as well as improvements to classical wet chemistry methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielectric environments. In this feature article, we describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qualitative features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of analytical and numerical methods for calculating extinction and scattering cross-sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangula...
9,086 citations
TL;DR: Semiconductor nanocrystals prepared for use as fluorescent probes in biological staining and diagnostics have a narrow, tunable, symmetric emission spectrum and are photochemically stable.
Abstract: Semiconductor nanocrystals were prepared for use as fluorescent probes in biological staining and diagnostics. Compared with conventional fluorophores, the nanocrystals have a narrow, tunable, symmetric emission spectrum and are photochemically stable. The advantages of the broad, continuous excitation spectrum were demonstrated in a dual-emission, single-excitation labeling experiment on mouse fibroblasts. These nanocrystal probes are thus complementary and in some cases may be superior to existing fluorophores.
8,542 citations