PVE300 - Trioptics
PVE300
Photovoltaic Spectral Response
EQE (IPCE), IQE
Quick and Accurate
The PVE300 system is a monolithic, turnkey
Using a monochromatic probe (any shape up to 6x6mm) and NMI traceable calibrated reference
solution for photovoltaic material and device
diodes, the PVE300 permits the quick and accurate determination of solar cell spectral response/
spectral characterisation; a key component in
EQE (IPCE). The additional measurement of cell transmittance and reflectance allows the
research, or as part of a production-line quality
determination of IQE.
process.
Measure all Device Types
Compatible with all types of photovoltaic devices, from silicon to 3rd generation devices: c:Si,
mc:Si, a:Si, µ:Si, CdTe, CIGS, CIS, Ge, dye-sensitised, organic/polymer, tandem, multi-junction,
quantum well, quantum dots etc...
Electrical Interface
A full range of detection electronics are available to accommodate the requirements of all device
types, including AC or DC operation, transformer, pre-amplifiers and lock-in amplifier with device
operation in short circuit or voltage biased.
Wide Spectral Range
The standard spectral range of 300-1100nm, may easily be extended to 1800nm and beyond.
Let the PVE300 do the Measurements for You
Fully automated through the USB interface and controlled by the Benwin+ windows software, the
PVE300 directly reports measurement results including spectral response, EQE, IQE and AM1.5 Jsc.
Flexible
A wide range of options include temperature-controlled vacuum mounts for substrate, superstrate or
packaged devices, integrating sphere accessory for measurements of total reflectance and
transmittance, a choice of single or multiple channel bias sources, including an AM1.5 matched bias
source and a motorised XY stage for device mapping.
Spectral Response
Reflectance
Overview of Operation
The sample under test is mounted horizontally on a temperature
controlled vacuum mount for thermal stability. A monochromatic
probe is made to be incident upon the sample under test; at
each wavelength is measured the photocurrent generated by the
device. Having measured the beam power with a detector of
known responsivity, spectral response and EQE can be directly
Determination of spectral response
(SR, A W-1) & external quantum
efficiency (EQE/IPCE, %)
Determination of total reflectance/
transmittance (R/T), to modify EQE
to yield internal quantum efficiency
(IQE, %)
obtained. The manner in which the device photocurrent is
measured, and the conditions under which this test is performed,
depends upon the type of device under test, described overleaf.
In many instances it is desirable to operate the cell in the
presence of a bias of one sun (1000 W m-2) to simulate use
conditions; indeed the use of such, with appropriate filtering, is
essential in the measurement of multiple junction cells to ensure
that the subcell under test be current limiting. In the case of
multiple junction and thin film devices, a voltage bias may also
be required.
Intervening a divert mirror in the beam relays the
EQE
IQE
monochromatic probe to a 6” diameter integrating sphere,
mounted on an optical rail to the upper of the PVE300 chamber,
for the measurement of device total reflectance and total
transmittance (where required). The EQE may be modified by
these latter measurements to determine the more fundamental
parameter of IQE.
PVE300 System Components
The PVE300 reunites the probe and bias sources at the sample plane where the
temperature-controlled vacuum mount is situated. A diverting mirror is inserted
to relay the probe to an integrating sphere for the measurement of transmittance
and reflectance.
Detection Electronics
The 417 unit houses the detection electronics of the PVE300
system. The detection electronics employed depends on the nature
of the device under test, discussed in detail overleaf.
Chopped Monochromatic Probe Source
A monochromatic probe is assembled from a TMc300, 300mm
focal length monochromator and a dual Xenon/ quartz halogen
light source, providing optimum illumination from the UV to the
NIR. The dual source may be fitted with a 218 optical chopper
(10 Hz-2 kHz) or a shutter-based 0-2Hz DC chopper. The 218
may be made to be arrestable to permit migration from the AC
to DC mode.
474– Transformer/ low noise amplifier
 Front-end for lock-in amplifier
 Transformer couples only AC signal
 Cell operated in short circuit conditions or
under voltage bias
 Transformer followed by low-noise amplifier
477– AC trans-impedance pre-amplifier
 Front-end for lock-in amplifier
 Six decades of gain
 Cell operated in short circuit conditions
 Useful in measuring experimental devices
and cell reflectance/ transmittance
DTR6 Integrating Sphere
The DTR6 integrating sphere
is mounted on a optical rail
to the upper of the PVE300
chamber to permit the
measurement of total
reflectance and total
transmittance.
497– DC/AC trans-impedance preamplifier & ADC
 Front-end for lock-in amplifier or main
detection electronics in DC mode
 Six decades of gain
 > 14 bit ADC
 Cell operated in short circuit conditions
495– Phase insensitive lock-in amplifier
 Recover optically chopped signal
 Operation 10-2000Hz
 Measures two orthogonal phases to return
vector sum
> 14 bit ADC
218– Optical Chopper Controller
 Controller for optical chopper housed in dual
source
 Reference output for lock-in amplifier
Constant Current Power Supply
A 605 constant current supply is required for each light
source (xenon, quartz halogen and solar simulator). The
excellent stability of the 605 ensures constant lamp output.
Relay Optic
A mirror-based relay optic images the apertured monochromator exit
port onto the sample plane, to provide a probe of any shape up to
6x6mm. Where the use of an aperture would exceed the desired
measurement bandwidth, the said aperture may be mounted outside the
exit slit and the monochromator translated on rails to move the aperture
to the imaged plane.
Software Control
The PVE300 is entirely automated through the USB interface and controlled
through the Benwin+ windows application.
The easy user interface allows quick and
easy system calibration, measurements of
spectral response, reflectance and
transmittance, determination of EQE/IQE
and switching bias sources. Data may be
analysed directly or exported to another
platform as required.
Solar Simulator
A variable intensity quartz halogenbased solar simulator with
computer controlled shutter is
mounted to the wall of the PVE300.
Light is transported via six-branch
fibre to ensure uniform illumination
in the sample plane.
Options include filter positions,
class B AM1.5 solar simulator and
multiple simulators for the
measurement of multiple junction
devices
Temperature Controlled Vacuum Mount
This 200x200mm mount provides the user with a convenient manner of electrical probing and allows controlling sample
temperature, by a quartet of Peltier devices, from 10-60°C , to counter the heating effects attendant to use of a solar simulator,
or for material investigation. For superstrate or packaged devices, alternative mounting and probing schemes are available. An
accompanying control unit houses the vacuum and water pumps and the bi-polar temperature control electronics.
Reference Detectors
The system is calibrated with
reference to NMI traceable
calibrated photodiodes (silicon
300-1100nm; germanium 8001800nm).
The Choice of Correct Detection Electronics
In general, standard techniques require that the spectral response of solar cells be tested under light biasing at 1000 W m-2 to simulate use conditions†. This
presents the problem of discriminating the photocurrent generated by the monochromatic probe from that generated by the solar simulator. In most cases,
this situation may be circumvented by optically chopping the monochromatic probe and recovering the AC signal with a lock-in amplifier having either a
transformer or trans-impedance amplifier front-end. Whilst the former input stage is preferred- since it does not pass the DC signal, the AC signal can be
given maximum possible gain- it only functions at elevated frequency, incompatible with certain types of cell. Indeed, in the case of certain DSSC cells, with
particularly slow electron transport, recourse is made to the use of a DC monochromatic probe and detection. The following are the recommended routes for
testing the solar cells of today.
Semiconductor and Organic Solar Cells
474 Transformer & 495 Lock-in Amplifier
Organic and DSSC Solar Cells
477/497 Pre-amplifier & 495 Lock-In
Amplifier
DSSC Solar Cells
497 and DC chopper
The fast electron transport mechanisms in most
semiconductor and some organic cells permit
exploitation of the preferred transformer
coupling method.
Where device response is slow, recourse is
made in the first instance to reduced chopping
frequency and the use of a trans-impedance
amplifier front-end to the lock-in amplifier.
Due to carrier transport mechanisms at play in
DSSC cells, it may be found necessary to
operate these cells at much slower chopping
frequencies or in the DC regime.
The monochromatic probe beam is optically
chopped at a frequency of 600 Hz and the cell
under test illuminated with a one sun solar bias.
The monochromatic probe beam is optically
chopped at a frequency of >10 Hz and the cell
under test illuminated with one sun solar bias
(or less to improve signal to noise).
The monochromatic probe beam is either run
DC or optically chopped up to 2Hz, and the cell
illuminated with a reduced level of solar bias.
The solar cell output is coupled by the 474
transformer, which passes only the optically
chopped signal. This signal is amplified and
passed to the lock-in amplifier. The device is
operated under short circuit conditions.
This technique is recommended for all
semiconductor (c:Si, mc:Si, a:Si, µ:Si, CdTe,
CIGS, CIS, Ge, tandem, multi-junction,
quantum well, quantum dots) and some organic
cells.
The solar cell output is passed through the
477/497 trans-impedance amplifier prior to
being passed to the lock-in amplifier. The
device is operated under short circuit
conditions.
The solar cell output is passed through a transimpedance amplifier and the cell response
recorded as a shutter in the dual source
switches on and off the monochromatic probe.
The device is operated under short-circuit
conditions.
This technique may be applied to organic and
some DSSC cells.
This technique may be applied to DSSC
technologies.
†IEC60904-8/ ASTM E1021 – 06/ ASTM E2236-05
PVE300 System Options
This PVE300 has been designed as a modular and configurable system to adapt to the measurement requirements of the PV technology to be studied. The
following provides a guide to the options available to enhance the functionality of the system.
Spectral Range
The TMc300 monochromator may be fitted
with up to three diffraction gratings to allow
measurement over wide spectral range in a
single scan. The standard range of 3001100nm may be extended to a maximum
range of 250-2500nm.
Integrating Sphere
The DTR6 integrating sphere is used to
collect the total transmitted or reflected
light from a sample (specular inclusive or
exclusive), with which information may be
modified the device EQE to determine the
more fundamental parameter of IQE.
Temperature Controlled Vacuum Mount
Whilst the electrical and thermal connection
of substrate devices is relatively trivial, the
same cannot be said of superstrate or
packaged devices. With an in-house design
service, Bentham can design a mount
suitable for your application.
DC/ Chopped Monochromatic Probe
The monochromatic probe may be operated
in the AC or DC regimes with either the 218
optical chopper (10 Hz-2 kHz) or a shutterbased 0-2Hz DC chopper. The 218 may be
made to be arrestable to permit migration
from the AC to DC mode.
Multiple Light Bias Sources
In the measurement of multi-junction
devices, multiple solar simulators are
required, one to bias the subcell under test
at one sun, the other filtered simulator to
ensure that the non– tested subcells are
sufficiently illuminated that they do not
current limit the tested subcell response.
XY Stage
Device uniformity and IPCE mapping may
be performed with the use of an XY stage,
upon which is mounted the temperaturecontrolled vacuum chuck, and the PVE300
enclosure height extended. The sample
position is scanned under the beam and
entirely controlled through Benwin+.
Voltage Biasing
In the case of multiple junction cells and
some thin film device, testing under voltage
bias is important. To this end, a Keithley
2400 Source Meter can be connected
directly to the transformer primary coil,
thereby biasing the device under test.
High Output Monochromatic Light
Source
For ultimate flexibility in the measurement
of multiple junction cells, a high irradiance
monochromatic probe, assembled from a
450W xenon lamp and 300mm focal length
monochromator provides a tuneable source
300-1100nm.
PVE300 Specifications
Monochromatic Probe
495 Phase Insensitive Lock-In Amplifier
474 Specification
Probe light source:
75W Xenon and 100W Quartz halogen
Frequency Range:
10Hz to 10kHz
Transformer DC resistance:
0.05Ω
Monochromator
configuration:
Triple grating, symmetric, single CzernyTurner, 300mm focal length
Sensitivity:
1mV to 1V in decade steps
Gain:
Trans. ~100x. Amp. 500x
Input Impedance:
100MΩ/25pf, pseudo differential
Bandwidth:
Adjustable fixed slit, 1-10nm typical
Amplifier bandwidth:
5Hz to >100kHz
Resolution:
0.3nm (1200g/mm); 0.6nm (600g/mm)
Dynamic Reserve:
40dB
+1%
Amplifier short circuit input
noise:
<1nV Hz-1/2 at 1kHz
Dispersion:
2.7nm/mm (1200g/mm);
5.4nm/mm (600g/mm)
Gain Accuracy:
Gain Stability
200ppm/°C
Amplifier Maximum Output:
10V
0.025° increments plus 90°
increments
Frequency of Operation:
600Hz typical
Minimum responsivity:
0.03 A W-1 nm-1 5nm BW, 2mm
probe typ.
300-1100nm (1200g/mm );
1100-2500nm (600g/mm)
Phase Control:
± 0.2nm (1200g/mm);
± 0.4nm (600g/mm)
Output Stability:
5ppm/°C to 500ppm/°C depending
on sensitivity
Relay Optic:
Mirror-based, 1.2x magnification
Time Constant:
10ms to 10s.
218 frequency range:
10-2 kHz
Probe size:
Up to 6x6mm
Phase Display:
3 digit LC display shows current
phase setting
DC chopper frequency range:
DC-2 Hz
Wavelength Range:
Wavelength accuracy:
Temperature-Controlled Vacuum Mount
Temperature control:
4x70W Peltier-based heat pump, watercooled hot side
Temperature range:
Temperature Feedback:
Temperature stability:
Reference Diodes
477/497 Specification
Diode & Range:
Silicon 300-1100nm;
Germanium 800-1800nm
Traceability
NPL/ PTB
Gain Ranges:
103-108 V/A
10-60°C
Maximum Input:
10mA
Centrally-positioned sensor situated 3mm
below sample plane
Input Impedance:
Virtual ground
Voltage Bias (Keithley 2400)
Gain Accuracy:
+1%
Voltage Range:
-20 to 20V
Gain Stability:
200ppm/°C
Current Limit:
1A
± 1°C
Solar Simulator
Transport to sample:
Branched glass fibre bundle
Bias source irradiance:
0-1.5 suns
Bias source uniformity:
Optical Chopper
Output Stability:
5ppm/°C to 500ppm/°C depending
on gain range
495/497 ADC
±1% over 1 cm2
Filter Option:
Two 50mm square filter holders
Resolution:
4 ½ digit BCD (0 to 19999) i.e. >
14 bit resolution
Source Options:
Quartz halogen/ Xenon/ Class B AM1.5
Conversion:
100ms
Input Range:
Linearity:
Automation
Software control:
BenWin+ Windows application
Interface:
USB
Contact Us
Bentham Instruments Limited
2 Boulton Road
Reading
RG2 0NH
United Kingdom
XY Stage
Travel:
300mm in X & Y
Resolution:
0.1mm
DTR6 Integrating Sphere
Port Size:
15mm Ø (5 &10mm Ø port
reducers supplied)
-0.2V to 9.8V
Coating:
Ba2SO4
< 0.025% departure from linearity
from zero to full scale
Detector:
Silicon/ Germanium/ SiliconInGaAs sandwich
Tel: 00 44 (0) 118 975 1355
Fax: 00 44 (0) 118 931 2971
Email: [email protected]
Web: www.bentham.co.uk
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