Showing papers on "Energy conversion efficiency published in 1981"
Book•
01 Oct 1981
TL;DR: In this paper, the solar source of light energy is described and quantified, along with a review of semiconductor properties and the generation, recombination, and the basic equations of photovoltaic device physics.
Abstract: Solar cell theory, materials, fabrication, design, modules, and systems are discussed. The solar source of light energy is described and quantified, along with a review of semiconductor properties and the generation, recombination, and the basic equations of photovoltaic device physics. Particular attention is given to p-n junction diodes, including efficiency limits, losses, and measurements. Si solar cell technology is described for the production of solar-quality crystals and wafers, and design, improvements, and device structures are examined. Consideration is given to alternate semiconductor materials and applications in concentrating systems, storage, and the design and construction of standalone systems and systems for residential and centralized power generation. Bibtex entry for this abstract Preferred format for this abstract
1,773 citations
TL;DR: In this article, a light single-sideband modulator, or frequency shifter, of integrated optics structure is proposed, which is confirmed by constructing and testing the device using Ti indiffused LiNbO 3 waveguides.
Abstract: A novel light single-sideband modulator, or frequency shifter, of integrated optics structure is proposed. The operation was confirmed by constructing and testing the device using Ti indiffused LiNbO 3 waveguides. The first demonstration of frequency shifting was carried out at 2 GHz, and either the upper or lower single-sideband output without carrier was obtained. Conversion efficiency of -5 dB was achieved with input drive power of 730 mW.
331 citations
TL;DR: In this article, the maximum conversion efficiency for the utilization of direct solar energy is investigated, and a fixed quantity of radiation is considered, and the essergy or potential work of the system is determined.
234 citations
TL;DR: In this paper, a clear valency electron controllability with substitutional impurity doping in the hydrogenated amorphous silicon carbide has been found, and a new type of a•SiC:H/a•Si:H heterojunction solar cell was developed.
Abstract: A clear valency electron controllability with substitutional impurity doping in the hydrogenated amorphous silicon carbide has been found. The amorphous silicon carbide is produced by the plasma decomposition of [SiH4(1−X)+CH4(X)] with the dopant gas of a B2H6 or PH3 system. Electrical and optical properties of doped amorphous SiC films are briefly demonstrated. Utilizing this a‐SiC:H as a wide‐band‐gap window material, we have developed a new type of a‐SiC:H/a‐Si:H heterojunction solar cell. A typical cell performance is Voc = 0.887 V, Jsc = 12.33 mA/cm2, fill factor = 0.653, and the conversion efficiency of 7.14% under AM‐1 illumination.
227 citations
TL;DR: In this article, it was shown that open-circuit operation is a reversible process and leads to the Carnot efficiency, if one defines the efficiency in the way that is usual in the theory of thermodynamic engines.
Abstract: An infinite stack ofp—n junctions with smoothly varying bandgap from ∞ to 0 is considered. AnI —V characteristic is derived, which is more correct than the classical exponential characteristic. It is shown that open-circuit operation is a reversible process and leads to the Carnot efficiency, if one defines the efficiency in the way that is usual in the theory of thermodynamic engines. If instead one uses the definition of efficiency usual in photovoltaics, open-circuit mode gives rise to zero efficiency. Then operation at maximum efficiency equals operation at maximum power and is not reversible.
173 citations
TL;DR: In this article, the authors reported energy conversion efficiency as high as 5.96% on polycrystalline transparent magnesium Zn3P2 diodes, 0.7 cm2 in area, tested under simulated AM1 illumination.
Abstract: Energy conversion efficiencies as high as 5.96% are reported on polycrystalline transparent magnesium Zn3P2 diodes, 0.7 cm2 in area, tested under simulated AM1 illumination. The transparent Mg films with low sheet resistivities are obtained by dc sputtering. The effective minority‐carrier diffusion length in Zn3P2 is estimated from spectral response measurements and correlates well with the measured short‐circuit current. Loss analysis of the present cells shows a practical upper limit of 9% in conversion efficiency.
159 citations
Proceedings Article•
01 Jan 1981
94 citations
TL;DR: In this article, the photovoltaic properties of p−Zn3P2/n −ZnO heterojunction solar cells prepared by sputter deposition of ZnO on Zn 3P2 substrates are reported.
Abstract: The photovoltaic properties of p‐Zn3P2/n‐ZnO heterojunction solar cells prepared by sputter deposition of ZnO on Zn3P2 substrates are reported. An active‐area power conversion efficiency of ∼2% has been obtained. The experimental results are discussed on the basis of an interface recombination model. The interface plays a significant role in determining the performance of the device.
87 citations
TL;DR: In this paper, the photovoltaic quantum yields and sunlight conversion efficiencies of a series of merocyanines in which the molecular properties have been varied systematically were investigated.
Abstract: Considerable progress has been made in improving the sunlight conversion efficiency of solid-state organic photovoltaic cells. Ghosh et al.1 report a 0.7% efficiency for a merocyanine dye Schottky barrier cell. We expect that improvements in energy conversion efficiency may follow if merocyanines of low ionization potential are used in photovoltaic cells, in which the dye layer contains a strongly electronegative dopant such as iodine. To test these ideas we report here the photovoltaic quantum yields and sunlight conversion efficiencies of a series of merocyanines in which the molecular properties have been varied systematically.
65 citations
TL;DR: In this paper, a glass laser was used to irradiate targets of various materials at ∼5 x 1014W/cm2 and the authors reported conversion efficiencies of between 1% and 0.1% for individual X-ray lines between 1.8 and 7.8 keV.
63 citations
TL;DR: In this paper, a chloroplast photoelectrochemical cell was proposed to generate large photovoltage and photocurrent, and has a power conversion efficiency close to 1%.
Abstract: Solar energy can be captured by photochemical or photoelectric processes in which a gradient of chemical potential can be generated using photochemical redox reactions. Photosynthesis is the most efficient system for quantum conversion and storage of solar energy1. Various biomimetic systems have been constructed as models for the conversion of light to electrical energy2–11. These biological photoelectrochemical cells have utilized macrocrystalline chlorophyll a (Chl a)2, chlorophyll liquid crystals deposited on the electrodes3–5 or incorporated into filters6, bilayer lipid membranes7, chloroplast membranes8, chloroplasts9 and bacterial reaction centres10,11. The power conversion efficiencies are mostly very low (≈0.002%). We describe here a chloroplast photoelectrochemical cell which generates large photovoltage and photocurrent, and has a power conversion efficiency close to 1%.
TL;DR: In this paper, the photovoltage follows the redox potential of the solution, and the Si-based photoelectrochemical cell is shown to achieve 2.87% light-to-electrical conversion efficiency at 101 mW/cm/sup 2/
Abstract: The photoelectrochemical cell: p-Si/VCl/sub 3/-VCl/sub 2/-HCl/C shows a 2.87% light-to-electrical conversion efficiency at 101 mW/cm/sup 2/ of natural sunlight. Over a 0.5 V range, the photovoltage follows the redox potential of the solution. Pinning of the p-Si surface Fermi level, previously proposed for this system, is ruled out. The advantages of photocathode-based semi-conductor-liquid junction solar cells (over photoanode-based systems) are demonstrated and discussed and comparisons made with the previously described p-InP photocathode (9.47% light-to-electrical conversion efficiency). Current-voltage characteristics of the cell are given at 101 mW/cm/sup 2/ sunlight. It is shown that the stability and efficiency of this cell is the best of any Si-based photoelectrochemical cell studied so far. (MJJ)
TL;DR: Mercury vapor has been used as a nonlinear frequency upconverting medium to generate peak powers of 5 kW at 1251 A in a bandwidth of 0.04 cm(-1) with a 10-Hz tunable system.
Abstract: Mercury vapor has been used as a nonlinear frequency upconverting medium to generate peak powers of 5 kW at 1251 A in a bandwidth of 0.04 cm−1 with a 10-Hz tunable system. The energy conversion efficiency is 0.3%. Parametric oscillation at the Hg resonance wavelength of 1849 A, as well as two other tunable (2ω1 − ω2) frequency-mixed signals producing radiation at 2085 and 1833 A, are reported.
TL;DR: In this paper, an extraordinary wave is normally incident on a large volume magnetoplasma, then below the second gyroharmonic, conversion into short-wavelength Bernstein waves is observed near the upper-hybrid layer.
Abstract: An extraordinary wave is normally incident on a large volume magnetoplasma, then below the second gyroharmonic, conversion into short-wavelength Bernstein waves is observed near the upper-hybrid layer. Significant conversion efficiency is attained in the optimum conditions. In the high power incidence, considerable electron heating due to the converted wave is found to be localized in the mode-conversion region.
TL;DR: It is found that dielectrics of lower refractive index give a higher cutoff wavelength, but the transition becomes more gradual, and it appears that using Al instead of Ag introduces appreciable absorption losses.
Abstract: Transparent heat mirrors of the antireflecting metal type with a dielectric/metal/dielectric structure are studied. It is found that dielectrics of lower refractive index give a higher cutoff wavelength, but the transition becomes more gradual. The angular behavior of these mirrors is also analyzed. The optimum mechanical efficiency obtainable with a plain collector and a carnot engine is given for different concentrations and refractive indices. Moreover it appears that using Al instead of Ag introduces appreciable absorption losses (~25-35%).
TL;DR: In this paper, a mechanically tuneable millimeter wavelength frequency doubler with 10 percent conversion efficiency at any output frequency in the range 100-260 GHz has been fabricated, with a fixed tuned instantaneous 1-dB bandwidth typically 5 percent of the center frequency.
Abstract: Mechanically tuneable millimeter wavelength frequency doublers typically exhibiting 10-percent conversion efficiency at any output frequency in the range 100-260 GHz have been fabricated. Output power varies from 10 mW at 100 GHz to 6 mW at 260 GHz, with a fixed tuned instantaneous 1-dB bandwidth typically 5 percent of the center frequency. A frequency tripler to 215-GHz output frequency is also described. For this device, a mechanically tuneable 3-dB bandwidth of 210 to 240 GHz was obtained, with a peak conversion efficiency of 6 percent at 4.8-mW output power.
Proceedings Article•
01 Jan 1981
TL;DR: TE-TM mode conversion was examined in two-layer epitaxial garnet films, with (Sc, Ga) substituted YIG films on a GGG substrate, and a novel waveguide optical isolator using the 45 degrees rotator is proposed.
Abstract: TE–TM mode conversion was examined in two-layer epitaxial garnet films, with (Sc, Ga) substituted YIG films on a GGG substrate. Mode conversion efficiency of 96% was observed in a single-mode waveguide over a 4.0-mm propagation distance at 1.15-μm wavelength. Mode conversion was increased by 2.0 × 10−4 optical anisotropy arising from the photoelastic effect of a 0.03% lattice mismatch between the guiding layer and the substrate. A 45° polarization rotator becomes possible because the TE and TM mode degeneracy is nearly complete. A novel waveguide optical isolator using the 45° rotator is proposed.
TL;DR: In this article, the techniques of fabricating low cost electrodeposited CdSe films for solar conversion cells are described and discussed, and the attainable goals and result of annealing, etching and doublesided illumination are discussed.
TL;DR: In this article, several novel chemical treatments are reported which reduce the deleterious effect of crystal edge sites on the photoconversion process in several of the layered semiconductors.
Abstract: Respectable light-to-electrical energy conversion efficiencies have been achieved with several of the layered semiconductors provided that only defect-free van der Waals surfaces (planes of selenium atoms) are exposed to the electrolyte. The transition-metal atoms, when exposed to the electrolyte, act as potent recombination centers for photogenerated carriers (surface states within the band gap) and severely degrade the energy conversion efficiency of the device. Dark current processes also occur at the unsaturated transition-metal sites and result in the back reaction of photogenerated redox species, which further degrades the efficiency of light-to-electrical energy conversion. Several novel chemical treatments are reported which reduce the deleterious effect of crystal edge sites on the photoconversion process in several of the layered semiconductors. Uncleaved single crystals of the transition-metal dichalocogenide (MoSe/sub 2/ or WSe/sub 2/) with van der Waals surfaces that had visible steps were treated with a 0.03 M solution of bis(1,2-diphenylphosphino)ethane (diphos) or 4-tert-butylpyridine (TBP). Improved power output decays under extended illumination with both treatments, but the improvement could be restored, in fact further improved, with additional treatments in TBP. (MWF)
TL;DR: In this paper, a Schottky barrier solar cell with a metal-insulator semiconductor structure has been fabricated on p-type InP. The open-circuit voltage and the energy conversion efficiency can be increased by introducing a thin oxide layer between the metal and the semiconductor.
Abstract: High‐efficiency Schottky‐barrier solar cells with a metal‐insulator semiconductor structure have been fabricated on p‐type InP. The open‐circuit voltage and the energy conversion efficiency can be increased by introducing a thin oxide layer between the metal and the semiconductor. The open‐circuit voltage and the energy conversion efficiency are 0.78 V and 14.5% under AM2 conditions.
TL;DR: In this article, high energy conversion efficiencies in the tunable output of an oscillator/amplifier dye laser system were measured ranging from 18% in near UV to about 5% in the IR.
TL;DR: In this paper, a dc-operated electroluminescent cell was constructed by molecular beam epitaxy and the lowest threshold voltage achieved was 3.8 V, and the highest power conversion efficiency and brightness were 7.6×10−5W/W(18 V, 0.0027 A/cm2) and 270 fL(16.8V, 1.25 A/ cm2), respectively.
Abstract: A Au/ZnSe:Mn/n‐GaAS dc‐operated electroluminescent cell was prepared by molecular beam epitaxy. The lowest threshold voltage achieved was 3.8 V, and the highest power conversion efficiency and brightness were 7.6×10−5W/W(18 V, 0.0027 A/cm2) and 270 fL(16.8 V, 0.25 A/cm2), respectively. These values are superior to any previously reported in ZnSe:Mn EL cells.
TL;DR: In this paper, the generation of photocarriers and their transport processes in poled poly(vinylidene fluoride) films under light illumination are discussed from the viewpoint of a ferroelectric property of β form crystals.
Abstract: The generation of photocarriers and their transport processes in poled poly(vinylidene fluoride) films under light illumination are discussed from the viewpoint of a ferroelectric property of β form crystals. We observed not only a pyroelectric current but an additional current due to anomalous photovoltaic effect. The open circuit photovoltage was estimated as 4×104 V, which exceeds the band gap potential of PVDF more than three decades. Because of the high resistivity of PVDF, the conversion efficiency of light to electric energy is still quite low (ca. 0.25%), but further improvements are suggested.
TL;DR: In this article, a general formulation of a semiconducting photovoltaic device is given, and the efficiency of this device is maximized with respect to tis structural parameters.
Abstract: A very general formulation of a semiconducting photovoltaic device is given. The efficiency of this device is maximized with respect to tis structural parameters. In this way it is shown that no solar cell structure can achieve a large efficiency than an infinite tandem cell, with bandgaps monotonically decreasing from infinity to zero, and of which each individual cell is a selective black body with its own appropriate bias voltage. This maximum efficiency is numerically calculated for various cell- and sun temperatures and concentration factors.
Patent•
[...]
20 Jul 1981
TL;DR: In this paper, a wind-powered electric generator using a concentrator structure and a focusing surface for focusing a wind stream onto a plurality of turbines, one of which is located within the concentrators structure, thereby providing for smaller structural size and increased conversion efficiency.
Abstract: A wind-powered electric generator using a concentrator structure and a focusing surface for focusing a wind stream onto a plurality of turbines, one of which is located within the concentrator structure, thereby providing for smaller structural size, as well as increased conversion efficiency.
TL;DR: In this article, a combination of surface chemical and voltammetric treatments was used to optimize the stability and performance of pSi/V2+−V3+, 4MHCl/C solar cells.
Abstract: In this letter we report a combination of surface chemical and voltammetric treatments that optimize the stability and performance of p‐Si/V2+−V3+, 4MHCl/C solar cells. The power conversion efficiency is 6.1% under 60‐mW/cm2 illumination. The results of capacitance‐voltage measurements and the improved solar cell properties are discussed on the basis of an electrolyte‐oxide‐semiconductor energy band diagram.
TL;DR: In this paper, a 25J, 50 ns laser pumped by opposed electron beams is described, and experiments with this device demonstrated a 9% intrinsic laser efficiency at power deposition rates of about 1 MW/cm3.
Abstract: A 25‐J, 50‐ns laser pumped by opposed electron beams is described. Experiments with this device demonstrated a 9% intrinsic laser efficiency at power deposition rates of about 1 MW/cm3. Parasitic control and narrowband output required for Raman‐compression experiments were demonstrated by injection locking the laser. Experiments showing an angle‐encoded extraction of energy from the medium (pulse stacking) with three pulses using a high‐gain three‐pass amplifier configuration are also described. The device utilizes triggering schemes of very low jitter suitable for synchronization to other components for optical pulse‐compression experiments.
TL;DR: In this paper, the authors investigated the photocurrent and electrical properties of photo cells operated in liquids and showed that the photometric properties of a photo cell increase with the increase in the permanent electric moment of molecules in liquid.
Abstract: Photocurrent and electrical characteristics are investigated for photo cells operated in liquids. Photocurrent increases with increase in the permanent electric moment of molecules in liquid. This effect is considered to be due to adsorption of polarizable molecules which reduce carrier recombination at the surface of photo cells.
Patent•
19 May 1981
TL;DR: In this paper, a p-i-n amorphous silicon photovoltaic cell of improved conversion efficiency is obtained by incorporating, as either the p or n type side of the cell exposed to the incident light, a semiconductor which satisfies the requirements that the optical band gap, eg.
Abstract: A p-i-n amorphous silicon photovoltaic cell of improved conversion efficiency is obtained by incorporating, as either the p or n type side of the cell exposed to the incident light, an amorphous semiconductor which satisfies the requirements that the optical band gap, Eg.opt, be not less than about 1.85 eV, the electric conductivity be not less than about 10-8 (Ω.cm)-1 the p-i-n junction diffusion potential, Vd, be not less than about 1.1 volts, and be formed of a substance represented by one of the general formulas, a-Si1-x Cx and a-Si1-y Ny.