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.
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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 ...
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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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References
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TL;DR: In this paper, les donnees sur l'influence d'un depot de CdS sur le Courant photoelectrique d'une electrode de TiO 2
146 citations
TL;DR: In this article, the Schottky barrier at the junction between a metallic contact and a semiconducting colloidal quantum dot film was elucidated experimentally using a combination of capacitance-voltage and temperature-dependent currentvoltage measurements.
Abstract: We elucidate experimentally a quantitative physical picture of the Schottky barrier formed at the junction between a metallic contact and a semiconducting colloidal quantum dot film. We used a combination of capacitance-voltage and temperature-dependent current-voltage measurements to extract the key parameters of the junction. Three differently processed Al∕PbS colloidal quantum dot junction devices provide rectification ratios of 104, ideality factors of 1.3, and minimal leakage currents at room temperature. The Schottky barrier height is 0.4eV and the built-in potential 0.3V. The depletion width ranges from 90to150nm and the acceptor density ranges from 2×1016to7×1016cm−3.
145 citations
TL;DR: In this article, photo-induced electron transfer in the direction from CdS to TiO2 was studied from the viewpoint of semiconductor sensitization, and the photoelectrochemical properties of a photoelectromechanical solar cell composed of cdSZnO and polysulphide solution was studied.
144 citations
TL;DR: In this paper, a detailed study of the optoelectronic processes occurring in ultrathin nanocrystal-conjugated polymer, poly(p-phenylene vinylene) (PPV) composites is presented.
Abstract: A detailed study of the optoelectronic processes occurring in ultrathin ${\mathrm{TiO}}_{2}$ nanocrystal-conjugated polymer, poly(p-phenylene vinylene) (PPV) composites is presented Composites of ultrathin films (about 100 nm) are studied spectroscopically and as the active medium in photovoltaic devices of the structure (Al/composite/indium tin oxide) By varying the weight ratio of the nanocrystals and using results of photoluminescence efficiency, photocurrent, and photovoltaic measurements and time-resolved microwave conductivity, we are able to construct a well-defined picture of the relevant processes in the composite: including exciton dissociation, charge transport, and recombination We combine the experimental results with a hopping model for charge transport in a nanocrystal lattice (random walk or biased random walk) to determine the probability of electron collection as a function of distance from a collecting contact in a nanocrystal lattice The combined results indicate that most photogenerated excitons lead to charge separation at the interface between the polymer and the nanocrystals above 20-wt % ${\mathrm{TiO}}_{2}$ nanocrystals, but the electron collection efficiency in photovoltaic devices is limited by fast recombination The transport model indicates that even for a relatively long recombination time and a well-ordered nanocrystal lattice, most of the collected charge will originate from the first several nanocrystal layers at the electrode rather than from sites throughout the film, due to the recombination process We also argue that the existence of a photocurrent in these and related devices is not necessarily evidence of charge transport through a network of the nanocrystals (or other component), as the quantum yields can be accounted for by interfacial charge transfer at the contact alone Quantum yields for collecting charge following direct band-gap excitation of the ${\mathrm{TiO}}_{2}$ are more than a factor of 10 larger than for excitation into the polymer, suggesting that either hole transfer to the polymer, or some preceding process, is rate limiting and much slower than the corresponding process following polymer excitation We also examine the key differences between the mechanisms underlying conjugated polymer:nanocrystal devices and conventional, silicon pn devices
144 citations
TL;DR: In this paper, the effect of charge accumulation in the metal layer results in Fermi-level equilibration raising the quasi-Fermi level of the composite close to the conduction band level of oxide semiconductor.
Abstract: Semiconductor-metal nanocomposites provide a simple and convenient way to tai- lor the properties of photocatalysts. Modification of semiconductor surface improves charge separation and promotes interfacial charge-transfer processes in nanocomposite systems. Charge accumulation in the metal layer results in Fermi-level equilibration raising the quasi- Fermi level of the composite close to the conduction band level of the oxide semiconductor. Phototransformations of such composites—including morphological changes, interfacial charge-transfer processes and photocurrent generation of TiO 2 -capped gold colloids—are presented in this review article.
142 citations