Quantum Zurich
FAST Quantum Efficiency Measurement System

Quantum-Efficiency-Measurements system perspective

The FAST Quantum Efficiency measurement system provides high-speed operation. As a result, the system is capable of performing a single measurement in only 5 seconds, independent of the wavelength range covered by the measurement.


The FAST Quantum Efficiency measurement system can be used as a complementary tool to a traditional monochromator based system to perform very fast preliminary analysis of the quantum efficiency of solar cells using a high throughput fabrication process, as well as to evaluate the homogeneity and reproducibility of the fabrication process of solar cells in large systems.


This is not a system made to compete with traditional monochromator based systems, but to rocket up solar cell manufacturing R & D projects. Quantum Efficiency measurements no longer cause bottlenecks, making fast analysis of a large amount of solar cells possible for researchers for the first time.


The use of solid-state Light Emitting Diodes (LED) technology as a light source is well known for its excellent long-term stability and quiet operation. It eliminates maintenance thanks to the absence of mobile parts inside the system and the long lifetime of the LED-based light source (typically > 10000 h). Additionally, it has lower energy consumption and is smaller in size, it has no health hazards and it is simple to install.


FAST Quantum Efficiency Measurement System

Quantum-Efficiency-Measurements System

The FAST Quantum Efficiency measurement system provides high-speed operation and excellent long-term stability. The high speed operation results from the parallel driving of a set of Light Emitting Diodes (LEDs) and the subsequent analysis of the signal by Fourier Transform techniques.


A series of 30 LEDs with a wavelength ranging from 382 nm to 1070 nm are simultaneously driven at different frequencies, the electrical signal induced by each photon at the solar cell is then amplified and analysed as a whole to extract the quantum efficiency by a FAST Fourier analysis.

FAST Quantum Efficiency Measurement System

Quantum-Efficiency-Measurements microcrystalline solar cell

The FAST Quantum Efficiency measurement system is capable of performing a single measurement in only 5 seconds, independent of the wavelength range covered by the measurement.


The system provides high-speed operation with a precision better than 2 %, and excellent long-term stability. A typical measurement that fulfils the above precision specification is performed by averaging a set of 4 measurements, which ultimately takes 20 seconds.


The figure shows a typical series of measurements to test the repeatability (precision) of the system. In particular, 10 measures every 5 minutes were performed on an amorphous-Silicon (a-Si) microcrystalline solar cell.


The following tables present a comparison between the short circuit density current (Jsc) obtained from quantum efficiency measurements of different kinds of solar cells measured by a traditional monocromator-based system (MONO) and the FAST Quantum Efficiency measurement system. The data corresponding to the FAST system represents an average of 4 measurements, for which it takes 20 seconds to obtain the whole spectral response.


As shown, the accuracy is better than 3 %, under the above measurement conditions.


Amorphous silicon solar cells(*)

Jsc [mA/cm2] MONO FAST Δrel %
Device 1 8.94 8.79 -1.68
Device 2 14.26 14.55 2.03
Device 3 14.00 13.83 -1.21

Microcrystaline silicon solar cells(*)

Jsc [mA/cm2] MONO FAST Δrel %
Device 1 20.50 20.87 1.80
Device 2 19.69 20.24 2.79
Device 3 14.44 14.28 -1.11

Micromorph tandem silicon solar cell(*)

Jsc [mA/cm2] MONO FAST Δrel %
Top 13.42 13.08 -2.53
Bottom 9.41 9.29 -1.27

(*) Quantum Zurich gratefully acknowledges the support of the Photovoltaics and Thin Film Electronics Laboratory, EPFL-STI-IMT NE-PVLAB, Neuchâtel (Switzerland) for providing the samples and performing the monochromator-based quantum efficiency measurements.



Specifications FAST Quantum Efficiency
Measurement System
Spectral range [nm] 382 - 1070
Number of wavelengths 30
Spot size [mm] 3-12
Working distance [cm] 3
Light source LED-based
Bias light High power LEDs:
red, blue, green and white
Bias voltage [mV]±5000
Measurement time [s] 5
Jsc repeatability <2 % (4 meaures averaged)
Jsc accuaracy <3 % (4 meaures averaged)
Beam spliter and light intensity
monitor photodetector
Yes
Current preamplifier Stanford SR570
A/D converter 12 bit
Probe connector Male 50 ohm BNC connector
Communication interface USB 2.0 (x4)
Software interface Windows XP/7/8/10
Operating temperature [°C] 10-40
Operating voltage [VAC] 240
Dimensions [cm] Electronic box: 45x28x38
Optical box: 37x14x30
Stanford SR570: 32x10x34
Weight [Kg] 26

FAST Quantum Efficiency Measurement System

Quantum-Efficiency-Measurements System

The FAST Quantum Efficiency measurement system consists of the following parts: 1) the electronic system, which is capable of driven individually each LED of the source light as well as the high power LEDs of the bias light, 2) the optical system, which allows the light to be focused into an external optical fiber cable, 3) the optical head, which is formed by a beam splitter and a photodetector to monitor the intensity of light that is captured by the solar cell, 4) the measurement chuck and 5) the current preamplifier, which consists of a Standford SR570 model (not shown in the figure). All is commanded, via 4 USB connectors, by a specific software with a graphical user interface.



FAST Quantum Efficiency Measurement System

Quantum-Efficiency-Measurements Software 1

Click & Measure


The FAST Quantum Efficiency measurement system is commanded by a graphical user interface that allows the user to measure the quantum efficiency with only a simple click: "measure device", without the need to set any parameters.


Additionally, the user can select the numbers of measurements to be averaged, and if necessary, activate the bias voltage or the bias light in a very intuitive way.


The software allows the user to measure a reference cell whose quantum efficiency is well known in order to calibrate the system.


Quantum-Efficiency-Measurements Software 3

Comparing data


The graphical user interface also allows the user to compare, in-situ and in a very simple and fast way, the quantum efficiency of multiple saved data.


The software linearly interpolates the curve drawn by the 30 measured points with a 10 nm step. These interpolated data are used together with the reference solar spectral irradiance (AM1.5G) to give an estimation of the current density generated by the solar cell.


FAST Quantum Efficiency Measurement System

Quantum-Efficiency-Measurements accesories optics

The FAST Quantum Efficiency measurement system is delivered with a simple and versatile measurement chuck which allows solar cells to be measured in all configurations. The contacting probes consist of spring-loaded pins placed on a flexible support, without wiring and with in-plane 360º mobility, which allows the probes to be positioned on the device in a confortable way.


The flexible optical fiber cable and the optical head can be positioned in whatever orientation to be easily adapted to customised measurement chucks.


FAST Quantum Efficiency Measurement Gallery

The following figures present a comparison between the quantum efficiencies of different kind of cells measured by a traditional monocromator-based system(*) and the FAST Quantum Efficiency measurement system. The data corresponding to the FAST system represents an average of 4 measurements.


Quantum-Efficiency-Measurements HIT solar cell

Heterojunction (HIT) solar cell
(6.25 cm2)


Quantum-Efficiency-Measurements micromorphe solar cell

a-Si Micromorph tandem solar cell
(1 cm2)


Quantum-Efficiency-Measurements monocrystalline solar cell

156 mm monocrystalline silicon solar cell
(two different devices)


(*) Quantum Zurich gratefully acknowledges the support of the Photovoltaics and Thin Film Electronics Laboratory, EPFL-STI-IMT NE-PVLAB, Neuchâtel (Switzerland) for providing the samples and performing the monochromator-based quantum efficiency measurements.


FAST Quantum Efficiency Measurement System Flyer.pdf


Quantum Zurich


CONTACT


Quantum Zurich
CH-8153 Rümlang
Switzerland

Phone:

+41 (0)76 82 82 120


E-Mail:

info@quantumzurich.com


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