Solar Cell QE/IPCE Measurement System - Solar Cell QE/IPCE Measurement System
What are QE and IPCE?
Quantum efficiency (QE) and Incident Photon to Charge Carrier Efficiency (IPCE) indicates the ratio of the number of photons incident on a solar cell to the number of generated charge carriers. Specifically, QE is a measure of the external efficiency, while IPCE is a measure of the internal efficiency; that is, the photons reflected back from the surface of the cell are not considered.
Both QE and IPCE measurements are of critical importance during the materials research and cell design stages. This is because the spectral response of the solar cell should be matched to the spectral distribution of sunlight to ensure highest efficiency in charge carrier generation.
How to Measure QE and IPCE?
The key to accurately measure the QE / IPCE of a solar cell is to quantify the intensity of monochromatic light incident to the device under test and how much photo-current is generated from this light.
The Solar Cell Scan100 employs the most common building blocks of a QE/IPCE system including probe and broadband bias light sources. These building blocks include for example: 150W ultra-stable Xenon light source, Omni-? monochromator, order sorting filters, and all reflective optics.
The system provides monochromatic light and software selectable broadband bias light source to a photovoltaic device. The bias source is provided to illuminate the test device with approximately 1 solar constant to simulate the actual operating environment. Utilization of a bias source requires an AC signal lock-in detection system. Firstly, the bias source is shuttered and the probe light modulated with an optical chopper to perform the system calibration of the reference detector. Secondly, both modulated probe and the bias light will illuminate an area of the solar cell. An additional detector preamplifier decouples the DC response of the detector due to the bias source so that only the AC component of the response is measured. The system also includes a motorized X-Y stage to provide a map of PV solar cell responsivity and wafer uniformity. Scan areas up to 156mmx156mm are possible.
Solar Cell Scan 100 Features
Full solar spectrum coverage from 300nm-2000nm
No need to upgrade the light source or monochromator subsystems. They are already capable for use in the Visible and Near InfraRed spectral regions for solar cell materials research.
- Vertical Measurement Optical Beam Path Design. Suitable for all kinds of solar cell QE measurement, and especially useful for dye-nanocrystalline solar cell (DSSC).
- Junction short circuit (Jsc) calculation
- Solar Cell QE Stability Measurement
- Adjustable Probe Beam Size
- Suitable for Solar Cell dimensions from 10 x 10mm2 up to 156 mmx 156mm
Tandem and Multilayer's PV device characteristic
A collimated parallel bias beam path with a 50mm square filter holder allows easy modification of the bias light condition. It is useful tool to define each layer's QE of PV device.
Parallel Bias Light Path
The bias light beam path can be easily fixed in one condition or adjusted to control the illumination condition of the bias light depending upon the exact requirement of the analysis required.
Reflectivity Measurement Capability
Determining the internal quantum efficiency of a PV solar cell requires measurement of the reflectance of the device. Reflectance from such cells is typically composed of both specular and some limited diffuse components. Although the diffuse reflectance can be small when compared to the specular component, it can still have a large effect on the device quantum efficiency. Solar Cell Scan 100 includes both specular and diffuse reflection measurement options. In addition, the unique optical design of the Solar Cell Scan 100 provides measurements of both power response and reflectivity of the test photovoltaic device, allowing the calculation of external and internal quantum efficiencies.
Temperature Adjustable Sample Holder
Working with the QE-F3 temperature controlled sample holder the working temperature of a solar cell can be changed from 5-40°C. This type of temperature response of the solar cell output may not be linear and can be used for evaluation of material defects.
XY Motorized stage for mapping the performance of - solar cells up to 156 x 156mm2
- QE uniformity mapping
- Reflectivity uniformity mapping
- Defects scanning by variable bias light intensity
AC/DC Pre-Amp Dual Measurement Modes- AC mode QE/IPCE measurement is useful for measuring fast response solar cells for example: amorphous silicon, monocrystalline silicon, microcrystalline silicon, polycrystalline silicon, CdTe, CIGS, GaAs.
- DC mode with dark sample chamber is used for slow response solar cells such as DSSC, organics solar cell.
- Both modes of measurement in the one instrument provide a versatile solar cell analysis tool for a wide range of applications.
Ordering Information and Specifications
| Solar Cell Scan 100 | 150W Xenon arc lamp for probe source, optical stability ?0.8%. Adjustable frequency optical chopper with control for insertion into or removal from optical path |
| 2. Probe light beam delivery: beam size is 3-10mm |
| 3. Motorized control monochromator with triple-grating turret |
| 4. Monochromatic light wavelength range : 300 - 2000 nm, with three gratings |
| 5. Motorised filter wheel with order-sorting filters |
| 6. Calibrated reference Si photodiode |
| 7. Rack-mount computer with Microsoft Windows OS® |
| 8. Wavelength accuracy : |
| a) ± 0.3nm?1200g/mm, blaze 300nm (1st grating) |
| b) ± 0.6nm?600g/mm, blaze 500nm (2nd grating) |
| c) ± 0.8nm?300g/mm, blaze 1250nm (3rd grating) |
| 9. <5 nm spectral bandwidth monochromatic light |
| 10. Monochromatic light modulation: 4 - 400 Hz (adjustable) |
| 11. Quantum Efficiency DC (DCS300PA) / AC (SR830) mode measurement |
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| 12. AC mode utilises the bias light source, optical chopper and lock-in amplifier detection |
| 13. DC mode utilises a pre-amp with data acquisition system, DCS300PA, with dual channel inputs (sensitivity 100nA), and 16 bit analogue to digital converter |
| 14. Test fixture : 156mm x156mm |
| 15. Single Spectral Response Scan less than 1 minute, |
| IPCE measurement less than 5 minute (@ 5nm step from 300nm -1000nm) |
| 16. Automatic operation, calibration and test report generation |
| QE-A1 | 150W Xenon Bias Light Source |
| White bias light source, optical stability ?0.8% |
| Bias light filter holders for multi-junction measurement |
| QE-C1 | Specular reflective measurement capability, Si detector 300-1100nm |
| QE-C2 | Integrating sphere diffuse reflectance measurement capability, Dual detector 300nm -1600nm |
| QE-D1 | XY Stage for QE uniformity scanning, 156mm x156mm |
| QE-F1 | Vacuum sample clamp test fixture, 156mm x156mm |
| QE-F2 | Thermoelectric temperature control @ 25 °C for QE-F1 |
| QE-F3 | 30x30mm Thermoelectric control sample holder temperature Control 5-40 °C |
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