Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence
  • G01N21/6489—Photoluminescence of semiconductors
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
  • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
  • H02S50/10—Testing of PV devices, e.g. of PV modules or single PV cells
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/64—Fluorescence; Phosphorescence
  • G01N2021/6491—Measuring fluorescence and transmission; Correcting inner filter effect
  • G01N2021/6493—Measuring fluorescence and transmission; Correcting inner filter effect by alternating fluorescence/transmission or fluorescence/reflection
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2201/00—Features of devices classified in G01N21/00
  • G01N2201/06—Illumination; Optics
  • G01N2201/065—Integrating spheres
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy

Definitions

• the present invention relates to a method for determining the maximum open circuit voltage of a photoconverter material.
• Solar cells for example in thin layers, such as amorphous silicon cells, CdTe, GaAs or other III-V compounds, or cells based on compound semiconductors, such as copper, galium and copper diselenide; indium, are based on a stack of layers of photoconverting materials and current collection materials.
• the optoelectronic properties of the material are determined so as to deduce the yield that could be obtained with a complete device.
• the invention proposes to meet this need by providing a non-contact method of determining the maximum open circuit voltage of a photoconverting material.
• the invention thus proposes a method for determining the maximum open circuit voltage (Vco) of a photoconverter material subjected to a measurement light intensity 10, the method comprising the following steps:
• the intensity of photoluminescence of the photoconverting material is measured by illuminating the photoconverting material by means of a first light source at a first light intensity II and at a first wavelength ( ⁇ ) corresponding to a first higher excitation energy; to the absorption energy (Eg) of the photoconverting material, the first light intensities (II) being substantially equal to the measurement light intensity 10
• the absorbance of the photoconverting material is measured at a second wavelength ( ⁇ 2) substantially equal to the photoluminescence wavelength of the photoconverting material by illuminating the photoconverting material by means of a second light source at the second length l wave ( ⁇ 2) and at a second light intensity 12, and
• the maximum open circuit voltage (Vco) of the photoconverting material is determined at the measurement light intensity 10 by means of the photoluminescence absorptivity and intensity measured at substantially the same wavelength, the light source and the photoconverter material being arranged so that the angular distributions of the rays incident on and emitted by the illuminated surface of the material and collected by the detector are substantially identical.
• the method according to the invention makes it possible to determine the open circuit voltage achievable by a given photoconverting material directly without the need for shaping or making contact.
• a method according to the invention may further include one or more of the following optional features, considered individually or in any combination:
• Ip L being the photoluminescence intensity of the photoconverting material measured by illuminating the photoconverter material at the first light intensity II, in particular it is the radiant energy density per frequency interval
• n V 2 being the optical index of the photoconverting material at the photoluminescence wavelength of the photoconverting material
• v is the frequency corresponding to the photoluminescence wavelength of the photoconverting material, h being the Planck constant,
• T being the temperature at the surface of the photoconverter
• Vco being the open circuit voltage of the photoconverting material
• the photoconverting material, the first and second light sources and the optical measuring device are arranged in such a way that the solid insolation angle of the photoconverting material is substantially equal to the solid angle of collection of the optical measuring device;
• the photoconverter is arranged in an integrating sphere structure so as to be indirectly illuminated by the first and second light sources; and - measurements of photoluminescence absorptivity and / or intensity are made by means of a diode or spectrometer, with or without modulating the signal at the sample level to increase sensitivity.
• the invention also relates to a method for determining the energy efficiency of a photoconverting material, the method comprising the following steps:
• the maximum open circuit voltage (Vco) of the photoconverting material is determined at a measurement light intensity 10 by a method according to the invention
• the photocurrent of the photoconverting material is determined by measuring the absorbency of the material at a third luminous intensity 13 substantially equal to the measurement light intensity 10 and at different wavelengths
• Vco the maximum open circuit voltage of the photoconverter material
• the invention also relates to a method for determining the extractable power of a photoconverter material illuminated by an intensity light source 10, the method comprising the following steps:
• the maximum open circuit voltage Vco of the photoconverting material is determined at a plurality of light intensities Ij comprise between 10/20 and 10 by a method according to the invention
• the photocurrent Icc of the photoconverting material is determined by a method according to the invention, the extractable power of the photoconverting material is determined by plotting Icc * Ij / I0 as a function of Vco (I).
• the extractable power is obtained by plotting Icc * lj / I0 as a function of Vco (lO) and considering the area of the largest rectangle inscribed between
• the sought power is equal to the surface of the rectangle.
• the photocurrent of the photoconverting material is determined by means of the following equation:
• Icc ⁇ ⁇ ( ⁇ ) ⁇ ( ⁇ ) ⁇ with
• Icc being the photocurrent of the determined photoconverting material
• ⁇ ( ⁇ ) being the incident light flux
• FIG. 1 is a schematic representation of a device for measuring the absorptivity of a photoconverter material according to one embodiment of the invention
• Figure 2 is a schematic representation of a device for measuring the photoluminescence intensity of a photoconverter material according to an embodiment of the invention.
• FIG. 3 represents a device allowing the implementation of a method according to the invention.
• the term "absorption and emission process equivalent photoluminescence" means absorption and emission processes that correspond geometrically by time reversal.
• the photoconverting material is illuminated so that the average angle and the angular aperture of the incident and emitted rays are the same.
• the photoconverting material is illuminated so that the light source and the photoconverting material are arranged in such a way that the angular distributions of the rays incident on and emitted by the illuminated surface of the material and collected by the detector are substantially identical.
• the inventors have observed that under open circuit conditions, the energy emitted by luminescence by a photoconverter material may be related to a measurement of the ability of the material to avoid losses by recombination of the electrons.
• the value of the open-circuit voltage Vco of a photoconverting material may appear in the relationship between the spectral radiation and the separation of the quasi-Fermi levels of the carriers qV.
• the inventors have observed that for a photoconverting material under certain conditions, the link between the spectral radiation and the separation of the quasis fermi levels of the carriers qV can be given by the generalized Planck e uation:
• I PL being the photoluminescence intensity of the material
• n v2 being the optical index of the photoconverting material at the photoluminescence wavelength of the photoconverting material
• c is the speed of the electromagnetic radiation in the vacuum
• v is the frequency corresponding to the photoluminescence wavelength of the photoconverting material, h being the Planck constant,
• T being the temperature at the surface of the photoconverter
• Vco being the open circuit voltage of the photoconverting material.
• the quantity q * Vco represents the maximum free energy that can be extracted from the photoconverter material, and which can be determined if the absorption and refraction indices, which make it possible to determine the absorptivity a (v) at the frequency v, are known .
• the amount q * Vco can be measured by means of a suitable optical device, such as an integrating sphere, using Kirchoff's law whereby the optical emissivity and absorptivity are equal to each frequency.
• the method according to the invention comprises a first step of measuring the photoluminescence intensity of the photoconverting material.
• the photoconverter material 10 can be arranged on one of the openings of an integrating sphere 12.
• the photoconverting material 10 is illuminated by means of a first light source, not shown.
• the first light source is disposed outside the integrating sphere 12 and illuminates the photoconverter material 10 through an opening 14 in the integrating sphere 12.
• the first light source illuminates the photoconverter material 10 at a first intensity II and at a first wavelength ⁇ corresponding to a first excitation energy greater than the absorption energy (Eg) of the photoconverter material 10.
• a device 16 making it possible to select the first wavelength ⁇ may be arranged between the first light source and the photoconverter material 10.
• the photoconverting material 10 is disposed in the integrating sphere 12 so as to be illuminated indirectly by the first light source.
• the processes of absorption of incident radiation and photoluminescence are equivalent, that is to say that they correspond geometrically by time reversal, or that the angular distributions of the rays incident on and emitted by the illuminated surface of the material and collected by the detector are substantially identical.
• the photoconverting material is illuminated so that the average angle of incidence and the angular aperture of the incident rays and photoluminescence are the same.
• the photoluminescence intensity of the photoconverter material 10 can be measured by a measuring device 18 placed on an edge of the integrating sphere 12. Any measuring device known to those skilled in the art may be used. In particular, it is possible to use a device comprising a diode allowing a light intensity measurement and a selective filter, for example a "notch" type filter or a diffraction grating, making it possible to filter the wavelengths so as not to measure the intensity that around the photoluminescence wavelength of the photoconverter material 10.
• the measuring device may be a spectrometer.
• the method according to the invention also comprises a step of measuring the absorbance of the photoconverter material 10 at one of the detectable photoluminescence emission wavelengths of said photoconverter material 10.
• the photoconverting material 10 may be arranged in an integrating sphere, for example the same as that used for measuring the intensity. photoluminescence.
• the photoconverting material 10 is illuminated by means of a second light source at the second length of the wave X2 and a second light intensity 12, arbitrary provided that it is adapted to the sensitivity of the detector used.
• the second wavelength X2 is substantially equal to the photoluminescence wavelength of the photoconverter material and the second light intensity 12 is substantially equal to the first intensity II.
• the photoconverter material 10 is disposed in the integrating sphere 12 in the same manner as for the photoluminescence measurement.
• the processes of absorption of incident radiation and luminescence are equivalent, that is to say that they correspond geometrically by time reversal, or that the angular distributions of the rays incident on and emitted by the illuminated surface of the material and collected by the detector are substantially identical.
• the solid angle of the rays incident on and emitted by the illuminated surface of the material and collected by the detector is 2n.
• the absorptivity of the photoconverter material 10 is obtained by measuring the reflectivity assuming that the transmission of the photoconverter material 10 is almost zero.
• a reflecting surface may be placed behind the photoconverter material 10 so as to return all the incident light.
• the generalized Planck equation is applicable and makes it possible to deduce the maximum open-circuit voltage Vco from the photoconverter material 10 of absorptivity and photoluminescence measurements.
• the photoluminescence intensity and the absorptivity of the photoconverter material 10 by means of an optical assembly allowing the solid insolation angle of the photoconverter material 10 to be substantially equal to the solid angle of collection of the optical measuring device.
• FIG. 1 An example of such an optical assembly is shown in FIG. 1
• the photoconverting material 10 is illuminated by a light source 20.
• the radiation from the light source 20 is focused on the photoconverting material by using a first optical device 22, comprising, for example, a lens convergent.
• the optical arrangement is configured so that the axis of the incident light radiation is substantially perpendicular to the plane of the photoconverter material 10.
• the incident radiation is preferably divided by means of a partially reflective plate placed between the first optical device 22 and the photoconverter material 10 so as to form an angle of approximately 45 ° with the incident light beam axis.
• the radiation reflected or emitted by photoluminescence by the photoconverter material 10 is redirected to a measuring device 24 via the semi-reflecting plate 25 and a second focusing device 26.
• the second focusing device may comprise a convergent lens, focusing the reflected radiation. or emitted by photoluminescence on the measuring device 24.
• the photoconverting material 10 can be insulated with a reference solar spectrum, the spectral portion close to and below the absorption threshold Eg of the photoconverting material being filtered so that the photoluminescence can be detected in the vicinity the absorption threshold Eg.
• the photoluminescence intensity in the emission band near the absorption threshold Eg makes it possible to go back to the extractable free energy of the material under this same insolation.
• the measurement of the absorbance of the photoconverter material 10 in a spectral range greater than the absorption threshold of the material and covering the spectrum to be converted makes it possible to obtain the maximum of the photocurrent which can be generated under these same conditions insolation.
• the photocurrent is limited by the amount of absorbed photons, in the usual cases where an absorbed photon can produce only a single pair electron / hole.
• the number and choice of points in the spectral range determine the accuracy of the value of the determined open-circuit voltage.
• the collection of photogenerated carriers is good and the internal quantum efficiency is indeed close to the absorptivity of the photoconverter material, for example between 80 and 90% thereof.
• Measurements of conductivity, or mobility, according to known methods can validate the hypothesis of efficient collection.
• the invention also relates to a method for determining the energy efficiency of a photoconverter material subjected to a measurement light intensity 10.
• the method of determining the yield may further comprise a step of determining the maximum open circuit voltage (Vco) of the photoconverter material at a measurement light intensity by a method according to the invention.
• the method for determining the yield according to the invention also comprises a step of determining the photocurrent of the photoconverting material.
• the photocurrent can be determined by measuring the absorbency of the material at different wavelengths so as to cover the spectrum to be converted. The number of determined values governs the accuracy of the determination made.
• Icc being the photocurrent of the determined photoconverting material
• ⁇ ( ⁇ ) being the incident luminous flux
• the inventors have observed that the incident luminous flux affects both the photocurrent but also the maximum open circuit voltage Vco.
• the plot of the photocurrent curve Icc as a function of the maximum open circuit voltage Vco for a range of incident flux makes it possible to obtain the voltage-current characteristic of the photoconverting material.
• the dark current namely the residual electric current in the photoconverter material in the absence of illuminance.
• the dark current makes it possible to obtain the amount of radiative recombination to obtain the radiative efficiency.
• the energy efficiency of the photoconverter material at light intensity 10 is proportional to the product of the maximum open circuit voltage Vco and the photocurrent.

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• Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• General Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Pathology (AREA)
• General Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Immunology (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
• Photometry And Measurement Of Optical Pulse Characteristics (AREA)
• Photovoltaic Devices (AREA)
• Testing Of Individual Semiconductor Devices (AREA)

Applications Claiming Priority (2)

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• 2010
  • 2010-02-05 FR FR1050845A patent/FR2956208B1/fr not_active Expired - Fee Related
• 2011
  • 2011-02-07 WO PCT/FR2011/050242 patent/WO2011095752A1/fr active Application Filing
  • 2011-02-07 CA CA2788911A patent/CA2788911C/fr not_active Expired - Fee Related
  • 2011-02-07 JP JP2012551670A patent/JP5889212B2/ja not_active Expired - Fee Related
  • 2011-02-07 AU AU2011212294A patent/AU2011212294B2/en not_active Ceased
  • 2011-02-07 EP EP11707464A patent/EP2531839A1/fr not_active Withdrawn
  • 2011-02-07 US US13/574,975 patent/US9297764B2/en not_active Expired - Fee Related
  • 2011-02-07 CN CN201180018136.XA patent/CN102947693B/zh not_active Expired - Fee Related

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