Showing papers on "Energy conversion efficiency published in 1979"
IBM1
TL;DR: In this paper, the authors used fluorescent wavelength shifting to enhance the spectral response and AM0 conversion efficiency of several types of solar cells, including polycarbonate and polysilicon.
180 citations
TL;DR: The photovoltaic properties of Schottky barier solar cells, made by dispersing particles of the x form of mental-free phthalocyanine in a binder polymer and sandwiching between NESA (SnO2/Sb) and aluminum electrodes, have been studied as discussed by the authors.
Abstract: The photovoltaic properties of Schottky barier solar cells, made by dispersing particles of the x form of mental‐free phthalocyanine in a binder polymer and sandwiching between NESA (SnO2/Sb) and aluminum electrodes, have been studied. A power conversion efficiency of over 6% for transmitted light at low power densities (0.06 W/m2) has been obtained for monochromatic irradiation at 670 nm. At peak solar power density (1400 W/m2) the extrapolated power conversion efficiency (η) for transmitted 670 nm irradiation decreases to 0.01%. The decrease in η with intensity was attributed to a space charge limitation due to nonlinear resistance. The devices exhibit Voc’s as high as 1.1 V, but are still limited by a field dependent quantum efficiency. Analysis of the action spectra of these devices revealed the formation of a thin photoactive depletion region (∼400 A) at the semiconductor/metal interface. These devices are capable of capturing 30% of the solar spectrum within the photoactive region. The effect of pig...
166 citations
TL;DR: Using beams of low-energy electrons, a free-electron laser can be operated as a continuously tunable, high-power source of laser radiation as discussed by the authors, and the beam can be recycled to increase the overall efficiency of the laser.
Abstract: Using beams of low-energy electrons ($El5$ MeV), a free-electron laser can be operated as a continuously tunable ($1000 \AA{}l\ensuremath{\lambda}l50 \ensuremath{\mu}$m), high-power ($Pg10$ kW, cw) source of laser radiation. With electrostatic accelerators the electron beam can be recycled to increase the overall efficiency of the laser. Wall power to laser power efficiencies greater than 10% are possible.
128 citations
TL;DR: In this paper, the effect of doping of MoSe2 (band gap 14 eV) as well as the influence of the electrochemical potential of the redox-couple in the electrolyte have been investigated in an effort to optimize solar cells based on layer compounds.
114 citations
TL;DR: By utilizing the vapor pressure difference between high-salinity and lowsalinity wvater, one can obtain power from the gradients of salinity, which eliminates the major problems associated with conversion methods in which membranes are used.
Abstract: By utilizing the vapor pressure difference between high-salinity and lowsalinity wvater, one can obtain power from the gradients of salinity. This scheme eliminates the major problems associated with conversion methods in which membranes are used. The method we tested gave higher conversion efficiencies than membrane methods. Furthermore, hardware and techniques being developed for ocean thermal energy conversion may be applied to this approach to salinity gradient energy conversion.
97 citations
TL;DR: In this paper, a thin film photovoltaic cell of CdS/Cu 2 S was designed and fabricated to achieve high energy conversion efficiency of 14-15% using a (CdZn)S/cu 2 S junction.
87 citations
69 citations
Patent•
16 Oct 1979TL;DR: In this article, a photoelectric conversion device such as a solar cell in which electrodes formed from a conductive paste make ohmic contact with the surfaces of impurity diffused layers respectively formed in a semiconductor substrate.
Abstract: A photoelectric conversion device such as a solar cell in which electrodes formed from a conductive paste make ohmic contact with the surfaces of impurity diffused layers respectively formed in a semiconductor substrate. The conductive paste contains ultrafine particles of silver and gold as its principal solid components. The conductive paste further contains, as its additional principal solid components, ultrafine particles of a metal having a eutectic temperature lower than that of silver when alloyed with the semiconductor and a powdery glass material not containing any lead oxide glass component. The electrodes provided by the conductive paste exhibit excellent electrical properties when the conductive paste is subjected to firing treatment at a temperature of about 600° C. Thus, when, for example, the semiconductor substrate is of n-type silicon and a p + -type diffused layer is formed in one of its major surfaces to form a p + /n junction of relatively small depth, the electrode making ohmic contact with the p + -type diffused layer does not penetrate through the p + /n junction and has a low contact resistance. The photoelectric conversion device such as the solar cell thus obtained can operate with a higher conversion efficiency than hitherto and can be manufactured at a lower cost than hitherto.
69 citations
TL;DR: Indium selenide n-type substrates made from ordinary grade elements, are suitable to make heterojunctions with semitransparent platinum layers Those low-cost devices have photovoltaic efficiencies for solar energy conversion under 6%, at the present time They can be readily improved to reach external efficiencies in the 10% range as mentioned in this paper.
TL;DR: In this article, a new buried-heterostructure laser with a buried optical guide has been developed, and a threshold current around 20 mA and a differential quantum efficiency as high as 85% are obtained under cw operation.
Abstract: A new buried‐heterostructure laser with a buried optical guide has been developed. A threshold current around 20 mA and a differential quantum efficiency as high as 85% are obtained under cw operation. This results in highly efficient laser operation, i.e., 35% power conversion efficiency at an optical output of 15 mW per facet, at which no degradation is observed over 3000 h at room temperature. Stable lowest‐order transverse mode and nearly isotropic laser beam (∼25°×35°) are obtained. Second‐order harmonic distortion is 55–65 dB below the fundamental level for 30% modulation with a 100‐MHz sinusoidal signal at 5 mW.
TL;DR: In this article, the design and performance characteristics of a tunable ir waveguide Raman laser pumped by a high power dye laser are described using SRS up to third Stokes order in compressed H2, the wavelength range from 0.7 to 7 μm has been covered without gaps.
Abstract: Design and performance characteristics of a tunable ir waveguide Raman laser pumped by a high power dye laser are described. Using SRS up to third Stokes order in compressed H2, the wavelength range from 0.7 to 7 μm has been covered without gaps. Taking advantage of a waveguide structure in the scattering chamber, energy conversion efficiencies better than 1% with power levels in excess of 80 kW for the third Stokes component have been achieved. The experimental results support the theoretical predictions that a 4-wave parametric process is responsible for the production of the third Stokes component.
TL;DR: In this article, the authors presented the results of a comprehensive theoretical analysis of tandem photovoltaic solar cells as a function of temperature and solar concentration ratio, where the I-V characteristics of the solar cells were assumed to be governed by the relation I = I 0 ( e qV/AkT − 1) with I 0 = K e −E G /BkT and A = B. The overall efficiencies of tandem cell stacks consisting of as many as 24 cells having energy gaps in the 07 to 36 eV range were calculated for temperatures of 200,
TL;DR: In this article, a compact long-life CO 2 -N 2 -He-Xe laser has been developed to produce 4-8 W on any one of ten CO 2 00°-10°0 and 00°1-02°0 transitions, selected by the laser signature technique.
TL;DR: In this article, an improvement in e−beam-pumped XeF laser efficiency is reported when the laser is operated at temperatures above 300 °K. The improvement is due mainly to improved energy extraction from the upper laser level as well as decreased lower level lifetime.
Abstract: Improvement in e‐beam‐pumped XeF laser efficiency is reported when the laser is operated at temperatures above 300 °K. The improvement is due predominantly to improved energy extraction from the upper laser level as well as decreased lower level lifetime. The highest intrinsic laser efficiency (laser energy out/e‐beam energy deposited in the active medium) observed at 3 amagats and 450 K is 5.5%. The temperature at which the highest efficiency is achieved is observed to increase with increasing gas density.
TL;DR: In this paper, an array of small Pb•O•Pb tunnel junctions was used to achieve a conversion loss as low as −5.8 dB and a single sideband mixer noise temperature of 10−40 K. The optimal conversion efficiency was obtained where the bias current microwave response was maximal.
Abstract: Quasiparticle mixing (biasing at the gap voltage) was studied in arrays of small Pb‐O‐Pb tunnel junctions. Coherent mixing at 9 GHz gave a conversion loss as low as −5.8 dB and a single sideband mixer noise temperature of 10–40 K. The optimal conversion efficiency was obtained where the bias current microwave response was maximal. The arrays of junctions were rugged, and gave a good impedance match to external circuitry.
TL;DR: In this paper, a bright green electroluminescent (EL) thin-film device for a flat-type display has been developed, which is constructed by a ZnS TbF3 thinfilm sandwiched between two semiconductive Y2O3 layers, achieving a typical brightness of 200 fL and a power conversion efficiency of 4×10−4 W/W.
Abstract: A bright green electroluminescent (EL) thin‐film device for a flat‐type display has been developed. The device is constructed by a ZnS : TbF3 thin‐film sandwiched between two semiconductive Y2O3 layers. A typical brightness of 200 fL and a power conversion efficiency of 4×10−4 W/W, values at least several times higher than reported elsewhere for green‐color thin‐film EL, are stably obtained at an excitation frequency of 5 kHz. This device is also capable of dc excitation with high efficiency (1×10−3 W/W) due to the existence of a semiconductive Y2O3 layer instead of an insulating layer. The semiconductive Y2O3 layer used in this device plays an important role in producing carriers in the ZnS active layer. Technical data on the characterization of the carrier injection mechanism and the device performance are presented and discussed.
TL;DR: In this article, single crystal n-GaAs in acetonitrile solutions were used to construct regenerative photoelectrochemical ical cells (PEC) for converting light directly into electrical energy.
Abstract: Regenerative photoelectrochem ical cells (PEC) were constructed utilizing single crystal n-GaAs in acetonitrile solutions. Solution redox couples (anthraquinone, p-benzoquinone, dimethyl terrocene, ferrocene, hydroxymethyl ferrocene, and tetramethyl-p-ph enylenediamine) whose standard redox potentim varied by over 1.2V, were photooxidized at the semiconductor electrode and reduced at a Pt counterelectrode converting light directly into electrical energy. A power conversion efficiency of 14% was observed for the n-GaAs electrode in a ferrocene-ferric enium acetonitrile solution at a radiant intensity of 0.52 mW/cm 2 of 720-800 nm light. The efficiency and stability were found to be very dependent upon the residual water concentration, radiant power, and concentration of electroactive species.
TL;DR: In this article, the authors presented the use of porous flat plate collectors to achieve efficient heat extraction from an energy absorbing solid, and its application to solar air heaters, and analyzed the temperature distribution within a gas-cooled porous flatplate having its surface exposed to the sun's energy.
TL;DR: In this paper, the authors have produced composite semiconductors by cosputtering CaF2 with either Ge or Si and measured their optical constants to compute the solar absorptance αs and thermal emittance eth.
TL;DR: In this paper, the authors measured the collection efficiency of photoexcited solar cells and showed that carrier generation requires an electric field in addition to light, and they also showed that the collector efficiency changes with the thickness of the barrier depletion layer.
Abstract: The collection efficiency ηc for photoexcited carriers is an important factor in solar cell efficiency. We have measured ηc for a‐Si : H‐Pt Schottky‐barrier solar cells and shown how it changes with the thickness of the barrier‐depletion layer. The results show that carrier generation requires an electric field in addition to light.
TL;DR: In this article, a tunable single-mode CO2 TEA laser was demonstrated to achieve power levels of up to 800 kW in 100nsec pulses and conversion efficiency of CO2 laser energy to D2O laser energy at 385 μm of up 0.4% have been obtained with a D 2O oscillator cavity.
Abstract: We demonstrate a 2‐GHz tunability of the 385‐μm stimulated Raman transition of D2O vapor optically pumped by the 9R (22) transition of a tunable single‐mode CO2 TEA laser. Power levels of up to 800 kW in 100‐nsec pulses and conversion efficiency of CO2 laser energy to D2O laser energy at 385 μm of up to 0.4% have been obtained with a D2O oscillator cavity. The TEA CO2 pump laser, which consists of a grating and etalon tuned oscillator followed by an amplifier chain, produced 25‐J 100‐nsec single‐mode pulses and was tunable ±1 GHz around the 9R (22) line center. The present results indicate that tunable single‐mode pump lasers are necessary in order to optimize high‐power optically pumped laser systems and to produce narrow‐linewidth spectral characteristics.
TL;DR: In this paper, the photovoltaic effect was used in order to study the efficiency of light conversion by the crystalline and anhydrous forms of Chl a. The results showed that the best conversion efficiency was obtained with O2, or air saturated with water.
Abstract: — A thin layer of chlorophyll a (around 2000 A). a p-type organic semiconductor. was sandwiched between two different metals. aluminum and silver. We used the photovoltaic effect in order to study the efficiency of light conversion by the crystalline and anhydrous forms of Chl a. When the photovoltaic cell is illuminated through the semi-transparent aluminum electrode. an action spectrum similar to the visible absorption spectrum of Chl a is obtained. The anhydrous form. always shows a maximum, in the red, at 672 nm and the crystalline one at 746 nm to 738 nm depending on the amount of water vapor present in the measuring area. The light conversion efficiency has been measured at the maximum absorption in the red for both forms of Chl a. For the anhydrous form, we found values as high as 0.036%, which is very significant even compared to 0.21%, the highest value found for the crystalline form. In both cases. the incident light power was approximately 10 μW on the cell. The light conversion efficiency of both forms of Chl a cells was found to depend on a combine effect of the nature of the gas (O1. N2. air. Ar. N2O. SF6, H2) and the amount of water vapor present in the measuring area. The best conversion efficiency was obtained with O2, or air saturated with water. This combined effect was very large for the crystalline form whereas the anhydrous form was only slightly affected.
TL;DR: In this article, the results of an investigation of 19 organic dyes pumped by a 1.7 MW discharge-pumped XeCl excimer laser are reported, and the dye-laser emission covered a wide wavelength range from 340 nm to 710 nm.
Abstract: Results of an investigation of 19 organic dyes pumped by a 1.7 MW discharge-pumped XeCl excimer laser are reported. The dye-laser emission covered a wide wavelength range from 340 nm to 710 nm.P-terphenyl shows efficient laser action. The highest energy conversion efficiency exceeds 40% in visible region. In comparison with 250 kW nitrogen laser pumping, higher efficiencies are obtained for most of these dyes in the same dye-laser configuration.
TL;DR: In this article, it is shown that by proper stepping up of the ripple magnetic field strength prior to electrostatic wave saturation, the efficiency can be substantially increased along with some bandwidth improvement and shortening of the device length.
Abstract: The electronic conversion efficiency of a free-electron laser using an intense relativistic electron beam in a rippled magnetic field as its active medium is limited mainly by the destruction of the coherent slow space-charge wave through particle trapping and the depletion of the available beam energy. It is shown that by proper stepping up of the ripple magnetic field strength prior to electrostatic wave saturation, the efficiency can be substantially increased along with some bandwidth improvement and shortening of the device length.
TL;DR: In this paper, the thermal resistance and temperature distribution in double-heterostructure lasers have been calculated taking into account the characteristics of the different layers, the internal quantum efficiency, and allotment of the dissipated power, in order to optimize their structure.
Abstract: The thermal resistance and temperature distribution in double-heterostructure lasers have been calculated taking into account the characteristics of the different layers, the internal quantum efficiency, and allotment of the dissipated power, in order to optimize their structure. The influence of the different layers in the heterostructure and of the electrical contact is analyzed. Thermal resistance of CW, shallow proton-implanted lasers has been determined experimentally using the technique that relies upon a null measurement of the wavelength of a single Fabry-Perot mode. Statistical results on some hundreds of lasers with different stripe widths ( 6-125 \mu m), mounted on different heat sinks (copper, silicon, beryllium oxide) are given and compared to theoretical values. The model we propose gives good agreement with experimental results. The 6 μm width stripe laser is of special interest because this laser is transverse monomode up to an optical power of 6 mW. A value of 22° C/W has been achieved in a reproducible manner for 6 \times 300 \mu m lasers mounted on copper heat sinks. The effectiveness of the bonding technique is demonstrated. Si and BeO heat sinks are suitable for many applications because of their chemical (V grove etching in Si) and thermal properties (better linear expansion coefficient match to GaAs). We show that the increase of thermal resistance so introduced is still compatible with long CW operation.
TL;DR: In this article, the optical properties of Ni cermet thin film have been investigated for a selective absorber of photothermal conversion devices, and fabrication technology is presented for cermet with fine particles of Ni embedded in SiO 2 or MgO (SiO 2 Ni,MgO Ni ).
Patent•
29 May 1979TL;DR: In this article, a solar cell having a copper-bearing absorber is provided with a composite transparent encapsulating layer specifically designed to prevent oxidation of the copper sulfide, which can be maintained at energy conversion efficiencies greater than one-half the original conversion efficiency for periods as long as thirty years.
Abstract: A solar cell having a copper-bearing absorber is provided with a composite transparent encapsulating layer specifically designed to prevent oxidation of the copper sulfide. In a preferred embodiment, the absorber is a layer of copper sulfide and the composite layer comprises a thin layer of copper oxide formed on the copper sulfide and a layer of encapsulating glass formed on the oxide. It is anticipated that such devices, when exposed to normal operating conditions of various terrestrial applications, can be maintained at energy conversion efficiencies greater than one-half the original conversion efficiency for periods as long as thirty years.