Complete Testing Solutions

Photovoltaic Testing Syatem (PTS)

This system includes either a 150W Xenon or 250W OTH lamp and a monochromator to tune the light source. A source meter used as an active load permits operating the test cell at various load conditions, includ- ing short-circuit, compensating for a series resistor re- quired to sense the current produced by the modulated monochromatic light. This sensed current plus a refer- ence signal at the frequency of the light modulation are both fed into the precision lock-in amplifier to allow measurement of the photocurrent generated by the modulated monochromatic light.
The PTS-1 features all the software required for l- V Curves and Spectral Response measurements. Main parameters of these measurements are displayed by the software, including the most important graphs typi- PTS Cell Testing System cally required by researchers and the industry. Option- ally, our software development group offers to develop whatever is required to meet your demands.
Unless a different request is made, the geometry of the light from the Monochromator is controlled to il- luminate only a small section of the solar cell (typically 3mm diameter), ensuring that 100% of the monochro- matic irradiance contributes to the output signal. NOTE: Spot size must be smaller than the 5mm diameter ref-erence Detector.
The PTS-1 system includes a SCIRUNSR IVTest EEEEE 7 | measurement system, precision lock-in amplifier and TITT y system software. The software controls the Monochro- y mator, source meter and lock-in amplifier to automati- cally measure the lV characteristics and SR versus wavelength, plotting the results) on screen and out- putting calculated values, including Voc, lsc, Pmax, Fill Factor, and the raw measurements to a standard file format.
Additionally, the PTS-1 can be upgraded with an optional light tight sample chamber, vertical adjustment components, sliding sample holder, and thermal control (either cooling or heating) for the sample holder. While these additions are not required for operation of the system, including them will ease your operation of the system. While the basic PTS-1 system offers researchers a good starting package for IV and SR measurements, the true power of the system is in its ability to seamlessly upgrade to a more versatile system. The PTS2 includes all the capabilities of the PTS1, plus the additional ability to measure Ouantum Efficiency. This improved system also includes a bias solar light and the necessary power supplies and controllers.



The PTS3 allows the user the same ability to measure IV, SR, and OE as the PTS-1 and PTS2 sys- tems, but adds the powerful techniques of Constant Photocurrent Method (CPM, PTS3-CPM), Dual Beam Photoconductivity Method (DBPM, PTS3-DBPM), or Photothermal Deflection Spectroscopy (PDS, PTS3- PDS).
In the CPM technique, the photocurrent is main- tained constant over the range of photon energy to get constant quasiFermi levels. Constant photocurrent im- plies that the steady state concentration and the lifetime of photogenerated electrons are constant, and thus the recombination mechanism is unchanged.
The CPM system illuminates the sample solar cell with a bias solar light source while a separate light source is modulated to cover a specific spectrum. The bias source ensures that the signal is not dominated by the non-linear response at low-level illumination of the cell, but rather gives a baseline response dependent on the wavelength of the modulated source (after the bias light signal is removed). This allows a highly precise measure of defect density of the cell, and as such gives researchers and manufacturers extremely sensitive in- formation for their work.
The DBPM system is based on the same setup as CPM, but has additional capability to vary the bias light source intensity. This changes the electron and hole quasiFermi levels to yield additional information about defect States. VVhile CPM measures bulk defect States below the dark Fermi level, DBPM can probe defects both below and above the Fermi level.

The PDS system can measure additional transi tions not observed in photoconductivity measurements, since it is not dependent on the Fermi level position. This technique is sensitive to surface, interface and bulk states. The modulated, monochromatic light periodi cally heats the medium in which the sample is embed ded. This in turn modulates the index of refraction near the film surface. The laser probe grazing the sample surface subsequently experiences a periodic deflection synchronized with the modulation of the intensity. The amplitude and phase of the deflection are measured and fed into a lock-in amplifier and thus, as the wave- length is varied, the deflection of the probe laser is a measure of the optical absorption spectrum of the sample.

The PTS3 comes with a fully integrated software package, capable of controlling every aspect of the system. Graphical and data output can be in a wide range of file types, and as Sciencetech may supply source code to customers that wish to further modify the system or integrate it into existing computer framework.

The PTS4 provides the same capabilities of the PTS1, PTS2, and PTS3-CPM systems for IV, SR, OE, and CPM measurements, and adds the Steady State Photoconductivity (SSP) method. The steady state photoconductivity measurements give information about the nature of defects, mobilitylifetime products, and the transport and recombination kinetics of photogenerated carriers. Since the states between quasi- Fermi levels act predominantly as recombination centres, steady state photoconductivity is sensitive to both the density and the nature of these states.

The addition of the SSP method to the PTS3 requires an upgrade to the existing software, as well as several modifications to the measurement components of the existing system. The iris, used in the PTS3-CPM, combined with the beam-splitter for intensity control, allows tighter manipulation of the flux values. A calibration photodiode is used to regulate the incident white light for the respective photon energies.




(PTS-1-SR) Spectral Response System
Sku: 175-9001

-IV Testing
-Spectral Response

The PTS-1-SR system includes a lamp and monochromator for a tuneable light source, coupled to a high sensitivity source meter with measurement software. The user-friendly system is the most powerful Spectral Response system currently on the market, but its true power is the ease of upgrading from the base PTS-1 to the more powerful PTS-2 (Quantum Efficiency) and PTS-3 (Constant Photocurrent Method). Designed for researchers who have limited budgets but want to start work immediately, this allows the ability to do baseline studies until additional funding for the full QE or CPM system becomes available.
For further information, please see the technical datasheet.





(PTS-2-QE) Quantum Efficiency/IPCE System
Sku: 175-9002

-IV Testing
-Spectral Response
-Quantum Efficiency/IPCE

The PTS-2-QE system allows an overall "external" quantum value which is considered the most important factor in cell testing. It includes all the Spectral Response equipment of the PTS-1, as well as a bias light and additional electronics and software to seamlessly allow user-friendly measurements of Quantum Efficiency. The PTS-2 can be upgraded to include Internal Quantum Efficiency measurements, or to include the necessary parts to allow Constant Photocurrent Method measurements (PTS-3).





(PTS-3-CPM) Constant Photocurrent Method System
Sku: 175-9003

The PTS-3-CPM allows users the same ability to measure IV, Spectral Response, and Quantum Efficiency as the PTS-1 and PTS-2, but adds the powerful Constant Photocurrent Method (CPM). The CPM system illuminates the sample solar sell with a bias solar light source while a separate light source is modulated to cover a specified spectrum. The bias source ensures that the signal is not dominated by the non-linear response at low-level illumination, but rather gives a baseline response dependent on the wavelength of the modulated source, allowing highly precise mesurements of defect density.
Please refer to the technical datasheet for additional information.





(PTS-3-DBM) Dual Beam Photocurrent Method
Sku: 175-9004

The PTS-3-DBPM has the same ability to measure IV, Spectral Response and Quantum Efficiency as the PTS-1 and PTS-2 systems, but adds the powerful technique of the Dual Beam Photoconductivity Method. The DBPM system is based on maintaining constant photocurrent over the range of photon energy to get constant quasi-Fermi levels. Furthermore, the DBPM system has the additional capability to vary the bias light source intensity. This changes the electron and hole quasi-Fermi levels to yield additional information about defect states.





(PTS-3-PTD) Photothermal Deflection System System
Sku: 175-9005

The PTS-3-PTD has the same capabilities to measure IV, Spectral Response, and Quantum Efficiency as the PTS-1 and PTS-2, but adds the powerful Photothermal Deflection method to the system. By the addition of a mounted laser firing across the substrate interface and embedding the samples within a particular material (supplied separately), allows the researcher the ability to measure significantly more information by determining the modulation of the laser as the monochromatic light from the monochromator is varied.
Please speak to a Sciencetech Technical Specialist for further information.





(PTS-4-SSP) Steady State Photoconductivity System
Sku: 175-9006

The PTS-4 allows the user the same ability to measure IV, SR, QE, and CPM as the PTS-1, 2, and 3 systems, and adds the powerful SSP (Steady State Photoconductivity) method to the extensive tools already available. Amorphous silicon materials exhibit monomolecular transport mechanisms, and the dependence of photoconductivity on generation rate can be studied by using SSP. Unlike bimolecular processes, monomolecular processes involve defect levels in the bandgap and it is directly related to extrinsic photoconductivity.

The steady state photoconductivity measurements give information aboutthe nature of defects, mobility-lifetime products, and the transport and recombination kinetics of photogenerated carriers. Since the states between quasi-Fermi levels act predominantly as recombination centres, steady state photoconductivity is sensitive to both the density and the nature of these states.





(WL-QE) White Light Quantum Efficiency/IPCE System
Sku: 175-9011

Designed for the photovoltaic researcher on a budget that still needs the reliability and accuracy that instruments from Sciencetech are famous for.

These systems include all the electronics, sources, and components to allow measurement of Quantum Efficiency/IPCE with high accuracy and repeatability. Please see the attached technical datasheets for full information on the range of specifications and capabilities. For a broader range of applications and even higher sensitivity, please see the Sciencetech PTS-2-QE (175-9002).

Please speak with your authorized Sciencetech technical support staff member to discuss if a White Light Quantum Efficiency System will meet your particular testing requirements.





(WL-SR) White Light Spectral Reponse System
Sku: 175-9010

Designed for the photovoltaic researcher on a budget that still needs the reliability and accuracy that instruments from Sciencetech are famous for.

These systems include all the electronics, sources, and components to allow measurement of Spectral Response with high accuracy and repeatability. Please see the attached technical datasheets for full information on the range of specifications and capabilities.
For a broader range of applications and even higher sensitivity, please see the Sciencetech PTS-1-SR (175-9001).

Please speak with your authorized Sciencetech technical support staff member to discuss if a White Light Spectral Response System will meet your particular testing requirements.





PTS Internal Quantum Efficiency/IPCE Upgrade
Sku: 175-9007

For IQE measurement the monochromator used in the external QE measurement system is fitted with an IQE attachment. This attachment is an integrating sphere sample chamber which allows the transmitted and reflected light by the solar cell to be captured and measured. For IQE measurements the cell is placed in the sample holder attached to the integrating sphere. A detector mated to the integrating sphere port orthogonal to the sample holders measures the reflected and transmitted light.
For cells that are small enough to fit in the IQE sample holder, bias light can be fed from a bias light source into the integrating sphere and onto the cell, so that the external QE itself can be measured with the IQE attachment. (As with the external QE unit, lock-in electronics and an I-V test system are used as well). In the case of larger cells however, a separate external QE/IPCE system is needed to obtain IQE based on full area measurements.