Thermal Change During Dental Polishing

Christensen, Gordon J.; Dilts, Walter E.

doi:10.1177/00220345680470050401

Cited by 17 publications

(9 citation statements)

References 5 publications

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“…For silicon, which has been the subject of extensive theoretical modeling as well as numerous electronic and optical measurements, the threshold for the onset of I.I. by photogenerated carriers is ∼ 3.1 eV, as borne out by several experimental studies [7,[43][44][45][46]. Together with the influence of silicon's band structure, energy relaxation through phonon emission also reduces the efficiency of impact ionization.…”

Section: Carrier-carrier and Carrier-lattice Interactions In Bulk Semmentioning

confidence: 99%

Multiple exciton generation in semiconductor nanocrystals: Toward efficient solar energy conversion

Beard¹,

Ellingson²

2008

Laser & Photonics Reviews

141

131

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Within the range of photon energies illuminating the Earth's surface, absorption of a photon by a conventional photovoltaic semiconductor device results in the production of a single electron-hole pair; energy of a photon in excess of the semiconductor's bandgap is efficiently converted to heat through electron and hole interactions with the crystal lattice. Recently, colloidal semiconductor nanocrystals and nanocrystal films have been shown to exhibit efficient multiple electron-hole pair generation from a single photon with energy greater than twice the effective band gap. This multiple carrier pair process, referred to as multiple exciton generation (MEG), represents one route to reducing the thermal loss in semiconductor solar cells and may lead to the development of low cost, high efficiency solar energy devices. We review the current experimental and theoretical understanding of MEG, and provide views to the nearterm future for both fundamental research and the development of working devices which exploit MEG. MEG E g E hνAbsorption of a single photon with energy in excess of two times the band gap, Eg, produces multiple excitons at the band edge. TEM picture of typical PbSe nanocrystals.

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Section: Carrier-carrier and Carrier-lattice Interactions In Bulk Semmentioning

confidence: 99%

Multiple exciton generation in semiconductor nanocrystals: Toward efficient solar energy conversion

Beard¹,

Ellingson²

2008

Laser & Photonics Reviews

141

131

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show abstract

“…[11][12][13] Thus, in Si the impact ionization efficiency was found to be only 5% (i.e., total quantum yield ϭ 105%) at a photon energy h Ϸ 4 eV (3.6 ϫ E g ), and 25% at h Ϸ 4.8 eV (4.4 ϭ E g ). 14,15 This large blueshift of the threshold photon energy for impact ionization in semiconductors prevents ma te rials such as bulk Si and GaAs from yielding improved solar conversion efficiencies. 6,15 However, in quantum dots, the rate of Auger proc esses, including the inverse Auger proc ess of exciton multiplication, is greatly enhanced because of carrier confinement and the concomitantly increased electron-hole Coulomb interaction (see Figure 2).…”

Section: Electron-hole Pair Multiplication In Quantum Dotsmentioning

confidence: 99%

Solar Cells Based on Quantum Dots: Multiple Exciton Generation and Intermediate Bands

Ĺuque¹,

Martı́²,

Nozik³

2007

MRS Bull.

216

122

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Semiconductor quantum dots may be used in so-called third-generation solar cells that have the potential to greatly increase the photon conversion efficiency via two effects: (1) the production of multiple excitons from a single photon of sufficient energy and (2) the formation of intermediate bands in the bandgap that use sub-bandgap photons to form separable electron–hole pairs. This is possible because quantization of energy levels in quantum dots produces the following effects: enhanced Auger processes and Coulomb coupling between charge carriers; elimination of the requirement to conserve crystal momentum; slowed hot electron–hole pair (exciton) cooling; multiple exciton generation; and formation of minibands (delocalized electronic states) in quantum dot arrays. For exciton multiplication, very high quantum yields of 300–700% for exciton formation in PbSe, PbS, PbTe, and CdSe quantum dots have been reported at photon energies about 4–8 times the HOMO–LUMO transition energy (quantum dot bandgap), respectively, indicating the formation of 3–7 excitons/photon, depending upon the photon energy. For intermediate-band solar cells, quantum dots are used to create the intermediate bands from the con fined electron states in the conduction band. By means of the intermediate band, it is possible to absorb below-bandgap energy photons. This is predicted to produce solar cells with enhanced photocurrent without voltage degradation.

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“…Excess heat production will also damage the pulp. 3 For these reasons the effects of lubrication may be of some importance.…”

Section: Discussionmentioning

confidence: 99%

The effects of lubrication on the temperature rise and surface finish of amalgam and composite resin

Jones

Billington

Pearson

2007

Journal of Dentistry

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Thermal Change During Dental Polishing

Abstract: Average handpiece speed and load values with nine commonly used instruments were compiled for polishing of silver amalgams. In vitro thermal effect of these instruments was recorded with and without air coolant. Temperature rise in dental pulps was less when air coolant was used.

Cited by 17 publications

References 5 publications

Multiple exciton generation in semiconductor nanocrystals: Toward efficient solar energy conversion

Multiple exciton generation in semiconductor nanocrystals: Toward efficient solar energy conversion

Solar Cells Based on Quantum Dots: Multiple Exciton Generation and Intermediate Bands

The effects of lubrication on the temperature rise and surface finish of amalgam and composite resin

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