Ossila Solar Cell I-V Test System (Automated)

1. Overview

The Ossila Solar Cell I-V Test System is a low-cost solution for reliable current-voltage characterisation of solar cells. The system is controlled by specially-designed software which can perform multiple I-V measurements, determine key metrics of solar cells, and measure these properties over long periods of time. The automated version of the system enables automatic switching between pixels, making measurements faster and easier.

2. EU Declaration of Conformity (DoC)

Company Name: Ossila Limited

Postal Address: Solpro Business Park, Windsor Street, Sheffield, S4 7WB, UK

Telephone number: +44 (0)114 2999 180

Email Address: info@ossila.com

Ossila Limited declares that the following product:

Product: Solar Cell I-V Test System - Automated (T2003A2 / T2003B2 / T2003C2 / T2003E2)

Serial number: T2003A2-xxxx, T2003B2-xxxx, T2003C2-xxxx, T2003E2-xxxx

Object of declaration: Solar Cell I-V Test System – Automated (T2003A2 / T2003B2 / T2003C2 / T2003E2)

The object of declaration described above is in conformity with the relevant Union harmonisation legislation:

• EMC Directive 2014/30/EU
• RoHS Directive 2011/65/EU

Signed:

Name: Dr James Kingsley

Place: Sheffield

Date: 07/12/2020

This section is also available in multiple other languages within the document.

3. Safety

3.1 Use of Equipment

The Ossila Solar Cell I-V Test System (Automated) is designed to be used as instructed. It is intended for use under the following conditions:

• Indoors in a laboratory environment (Pollution Degree 2)
• Altitudes up to 2000m
• Temperatures of 5°C to 40°C; maximum relative humidity of 80% up to 31°C.

The unit is supplied with a 24 VDC/2A power adapter with a power cord for the country of purchase, in accordance with European Commission regulations and British Standards. Use of any other electrical power cables, adaptors, or transformers is not recommended.

3.2 Hazard Icons

The following symbols can be found at points throughout the manual. Note and read each warning before attempting any associated operations:

3.3 General Hazards

Before installing or operating the Solar Cell I-V Test System (Automated), there are several health and safety precautions which must be observed to ensure safe installation and operation.

3.4 Power Cord Safety

Emergency power disconnect options: use the power cord as a disconnecting method and remove from wall. To facilitate disconnect, make sure the power outlet for this cord is readily accessible to the operator.

3.5 Servicing

If servicing is required, please return the unit to Ossila Ltd. The warranty will be invalidated if:

• Modification or service has been carried out by anyone other than an Ossila engineer.
• The Unit has been subjected to chemical damage through improper use.
• The Unit has been operated outside the usage parameters stated in the user documentation associated with the Unit.
• The Unit has been rendered inoperable through accident, misuse, contamination, improper maintenance, modification, or other external causes.

3.6 Health and Safety - Servicing

Servicing should only be performed by an Ossila engineer. Any modification or alteration may damage the equipment, cause injury, or death. It will also void your equipment's warranty.

4. Requirements

The system requires a computer running Windows (Vista or newer) with an available USB port or a network connection. Further details are given in Table 4.1.

5. Unpacking

5.1 Packing List

The standard items included with the Ossila Solar Cell I-V Test System – Automated are:

• Ossila Solar Cell I-V Test System – Automated.
• 24 VDC / 2A power adapter with a cord set specifically for country of operation (UK, USA, EU, or AU).
• USB-B cable.
• USB memory stick pre-loaded with the user manual, quality control data, and software installer.
• Printed copy of the user manual.

5.2 Damage Inspection

Examine the components for evidence of shipping damage. If damage has occurred, please contact Ossila directly for further action. The shipping packaging will come with a shock indicator to show if there has been any mishandling of the package during transportation.

6. Specifications

The Solar Cell I-V Test System – Automated specifications are shown in Table 6.1.

7. System Components

The Solar Cell I-V Test System – Automated comprises three items: the Solar Cell I-V Test System, power adaptor, and the Solar Cell I-V software.

Figure 7.1. Solar Cell I-V Test System: A diagram of the Ossila Solar Cell I-V Test System unit, a rectangular box with a slot on the front for a sample holder.

Figure 7.2. The 18V DC power adapter: A diagram of the 18V DC power adapter, a small rectangular box with a cable and plug.

Figure 7.3. Solar Cell I-V Test System software: A screenshot of the Ossila Solar Cell I-V Test System software, showing a user interface with various settings and a graph plotting current density against voltage.

8. Installation

1. Install the Solar Cell I-V software on your PC.
   • Run the file 'Ossila-Solar-Cell-IV-Installer-vX-X-X-X.exe' on the USB memory stick provided.
   • Follow the on-screen instructions to install the software.
2. Connect the 24 VDC power adaptor to the power socket on the rear of the unit.
3. Connect the unit to your PC using the provided USB-B cable, or an Ethernet cable if preferred.

The Solar Cell I-V software can also be downloaded from www.ossila.com/pages/downloads.

9. Operation

9.1 Measurement Types

The Solar Cell I-V software can perform three different types of measurements. Each measurement type can be selected using the tabs at the top of the window. The available measurements are:

1. Solar Cell Characterisation (Section 9.1.1).
2. Solar Lifetime Measurement (Section 9.1.2).
3. Stabilised Current Output (Section 9.1.3).

Each measurement type requires several settings to be selected before it can be performed. Settings that are shared between all measurements are detailed in Section 9.2. Measurement-specific settings are detailed in Sections 9.4, 9.5, and 9.6.

9.1.1 Solar Cell Characterisation

The Solar Cell Characterisation tab performs current-voltage (I-V) measurement and analysis of solar cells. The analysis calculates the following properties:

• Power conversion efficiency (PCE)
• Fill factor (FF)
• Short-circuit current density (Jsc)
• Open-circuit voltage (Voc)
• Shunt resistance (Rsh)
• Series resistance (Rs)

Figure 9.1. Solar Cell I-V software: The Solar Cell Characterisation tab: Screenshot of the Solar Cell Characterisation tab in the software, showing input fields and a plot area.

9.1.2 Solar Lifetime Measurement

The Solar Lifetime Measurement tab tracks PCE, FF, Jsc, and Voc over time by performing periodic I-V measurements and analysis. Between I-V measurements, the solar cell can be held at short-circuit, open-circuit, or maximum power.

Figure 9.2. Solar Cell I-V software: The Solar Lifetime Measurement tab: Screenshot of the Solar Lifetime Measurement tab, showing input fields and multiple plots tracking PCE, FF, Jsc, and Voc over time.

9.1.3 Stabilised Current Output

The Stabilised Current Output tab lets you measure the evolution of the photogenerated current at specific voltages.

Figure 9.3. Solar Cell I-V software: The Stabilised Current Output tab: Screenshot of the Stabilised Current Output tab, showing input fields and a plot area.

9.2 Quickstart Guide

1. Start the Ossila Solar Cell I-V software. The window shown in Figure 9.1 will open.
2. Choose a measurement type as described in Section 9.1.
3. Place your sample in the test board.
4. Place the test board beneath your solar simulator.
5. Set the appropriate settings in the software (explained in more detail in Sections 9.4 - 9.8).
   • Set ‘Pixel Switching' to 'Automated'.
6. Open the shutter of your solar simulator.
7. Click the 'Measure' button.
   • For each pixel, measurements are performed using the chosen measurement settings.
   • After the measurement has completed, the results are displayed in the central plot.
   • This process is repeated until all pixels have been measured.
8. If automatic saving is turned on, the measurement data and settings will then be saved.

9.3 Shared Software Settings

The settings in these sections are shared between all measurement types.

9.3.1 Connection

Figure 9.4. Connection settings: Screenshot of the Connection settings within the software, showing dropdowns for Connection Type and System Address.

• (I) Connection Type: Select the type of connection you are using (either USB or Ethernet). Any connected units will be automatically detected when a selection is made and the 'System Address' box will be populated. The software will search for units connected via USB on start-up. To rescan for connected units (in case the connection is changed), click the refresh icon next to the 'System Address' box.
• (II) System Address: Select the COM port or IP address of the connected unit you intend to use (USB and Ethernet connection respectively). This box will be populated automatically with the addresses of any units connected to the computer via the method selected in the ‘Connection Type' box.

9.3.2 System Settings

Figure 9.5. System settings: Screenshot of the System settings, showing dropdowns for Voltage Source and Current Range, and an input for Samples per Point.

• (I) Voltage Source: 'SMU 1' will be automatically selected when pixel switching is set to 'Automated'.
• (II) Range: Select the range of currents to be used for the measurement. This defines the upper limit and accuracy of current measurements that can be performed by the unit. The values for each range are given in Table 9.1. The maximum current values for each range are also shown in the range selection box.

9.3.3 Device Details

Figure 9.6. Device Details settings: Screenshot of the Device Details settings, showing options for Pixel Switching, Pixels to Test, Pixel Area, and Inverted Device.

• (I) Pixel Switching: Select 'Automated' in the pixel switching setting.
• (II) Pixels to Test: Select which pixels to measure. The pixel numbers are labelled on the test board.
• (III) Pixel Area: Set the area in cm² of each pixel in the device.
• (IV) Inverted Device: Set whether the device to be measured is inverted. This option should be on if the anode of your device connects to the ‘cathode’ pins in the device holder.

9.4 Solar Cell Characterisation Settings

9.4.1 Measurement Settings

Figure 9.7. Measurement Settings for the solar characterisation and lifetime measurements: Screenshot of Measurement Settings for solar characterisation and lifetime measurements, showing fields for Start Voltage, End Voltage, Voltage Increment, Voltage Settle Time, Illumination, and Hysteresis I-V.

• (I) Start Voltage: Set the voltage in volts at which to start the current-voltage measurement. This can be set between -10 V and +10 V.
• (II) End Voltage: Set the voltage in volts at which to end the current-voltage measurement. This can be set between -10 V and +10 V.
• (III) Voltage Increment: Set the step size in volts for changing the voltage during current-voltage measurement.
• (IV) Voltage Settle Time: Set the time in seconds between applying a voltage and measuring the current. This has a maximum of 10 seconds.
• (V) Illumination: Set the illumination intensity (in mW.cm⁻²) being used during the measurement.
• (VI) Hysteresis I-V: This option performs a reverse current-voltage measurement after the forward current-voltage measurement has completed. This reverses the set start and end voltages and uses the same voltage increment and settle time as the forward measurement.

9.5 Solar Lifetime Measurement Settings

9.5.1 Measurement Settings

Figure 9.8. Measurement Settings for the solar characterisation and lifetime measurements: Similar to Figure 9.7, showing Measurement Settings for solar characterisation and lifetime measurements.

• (I) Start Voltage: Set the voltage in volts at which to start the current-voltage measurement. This can be set between -10 V and +10 V.
• (II) End Voltage: Set the voltage in volts at which to end the current-voltage measurement. This can be set between -10 V and +10 V.
• (III) Voltage Increment: Set the step size in volts for changing the voltage during current-voltage measurement.
• (IV) Voltage Settle Time: Set the time in seconds between applying a voltage and measuring the current. This has a maximum of 10 seconds.
• (V) Illumination: Set the illumination intensity (in mW.cm⁻²) being used during the measurement.
• (VI) Hysteresis I-V: This option performs a reverse current-voltage measurement after the forward current-voltage measurement has completed. This reverses the set start and end voltages and uses the same voltage increment and settle time as the forward measurement.

9.5.2 Lifetime Parameters

Figure 9.9. Lifetime Parameters settings: Screenshot of Lifetime Parameters settings, showing fields for Duration, Time Between Repeats, and Hold Voltage.

• (I) Duration: Set the total duration in hours of the lifetime measurement.
• (II) Time Between Repeats: Set the time interval in minutes between performing repeat current-voltage measurements of the device.
• (III) Hold Voltage: Set the voltage that all pixels will be held at between measurements. This can be set as:
  • Short-Circuit – hold at 0 V.
  • Maximum Power – hold at the average maximum power point determined from most recent current-voltage curve.
  • Open-Circuit – hold at the average open-circuit voltage determined from the most recent current-voltage curve.

As the voltage source is only a single channel, the hold voltage will be the same for all pixels being tested.

9.6 Stabilised Current Output Settings

9.6.1 Measurement Settings

Figure 9.10. Experimental Parameters settings for the Stabilised Current Output: Screenshot of Experimental Parameters settings for the Stabilised Current Output, showing fields for Voltage, Total Time, and Time Interval.

• (I) Voltage: Set the voltage to apply to the sample for the measurement. This can be set between -10 V and +10 V.
• (II) Total Time: Set the total length of the measurement in minutes.
• (III) Time Interval: Set the time between each current measurement in seconds. This has a minimum of 0.1 seconds.

9.7 Saving and Loading Settings

Figure 9.11. Controls for saving and loading settings profiles: Screenshot showing controls for saving and loading settings profiles, with buttons for "Save Settings" and "Load Settings", and a dropdown for "Settings Profiles".

• (I) Save Settings: Saves the current settings as a profile that can be loaded quickly for use at another time. When clicked, you will be prompted to name the settings profile. If the name is already in use, you will be asked if you wish to overwrite the previous profile. The name cannot contain the characters: \ / : * ? " < > |. You can change the default settings by choosing the name ‘Default'. The settings profile will be added to the drop-down box using the given name.
• (II) Load Settings: Opens a dialog box to navigate to a settings file that has been created as part of a previous measurement. The settings fields will be populated with the values in the settings file.
• (III) Settings Profiles: Select a saved settings profile from the drop-down box. The settings fields will be populated with the saved values. Settings profiles can be deleted by selecting the profile, and then clicking the red 'delete' icon next to the drop-down box.

9.8 Saving Results

Figure 9.12. Saving measurement data settings: Screenshot of Saving measurement data settings, showing options for "Save After Measurement", "Save Directory", "Experiment Name", "Device Label", and "Save Results" button.

• (I) Save After Measurement: Set whether the measurement data will be saved after the measurement has completed.

Warning: Automatic saving can be turned off for lifetime measurements. However, manual saving is unavailable for lifetime measurements, so you will not be able to save your data if it is off.

The program allows for data to be saved automatically (and manually) once the measurement is complete. To enable or disable automatic saving, choose the appropriate option from the drop-down box. For automatic saving, the 'Saving' fields must be filled in before the measurement can start, these are detailed below. The 'Save Results' button is enabled once a measurement has been completed.

For all measurements, a save directory must be specified. This can be done either by:

• Manually typing the directory into the 'Save Directory' field,
• Copy and pasting from your file explorer,
• Clicking the 'Select Directory' button, which will open a dialog box to allow the selection of a folder to save to.

All output files are comma separated variable (.csv) files.

• (II) Save Directory: Set the directory in which to create the data files. This can be filled in by manually typing the directory, copy and pasting from your file explorer, or clicking the 'Select Directory' button.
• (III) Experiment Name: Set the name of the folder that the data will be saved into. For solar cell characterisation measurements, this will also be used to name the file containing the device properties. This field cannot contain the following characters: \ / : * ? " < > |
• (IV) Device Label: Set the name of the device being tested. This is used to label the files for I-V data and measurement settings. This field cannot contain the following characters: \ / : * ? " < > |
• (V) Save Data Format: All data is saved as .csv (comma separated value) files. All data will be saved into a folder with the Experiment Name.

Figure 9.13. Solar Cell Characterisation save data format: Diagram illustrating the file structure for Solar Cell Characterisation save data format.

Figure 9.14. Stabilised Current Output save data format: Diagram illustrating the file structure for Stabilised Current Output save data format.

Figure 9.15. Solar Lifetime Measurement save data: Diagram illustrating the file structure for Solar Lifetime Measurement save data.

9.9 Controls

Figure 9.16. Controls for the measurements: Screenshot showing the main measurement controls: "Measure" and "Cancel" buttons.

• (I) Measure: Clicking this button will start the measurement using the chosen settings. This button cannot be clicked if the software has not detected the test system.
• (II) Cancel: Stops a measurement that is currently in progress. If the measurement is stopped before it completes, the user will be unable to save the experimental data.

9.10 Test Device

The system is shipped with a test device that can be used to verify the correct operation of the system by mimicking the response of a solar cell. It has semiconductor photodiodes arranged in the geometry of the substrate pixels. The appearance of the test device will depend on the substrate system being used (Figure 9.17).

Figure 9.17. Test device configurations: Images of different test device configurations (S211, S101, S171, S2006C1).

9.10.1 Taking a Measurement

1. Place the test device in the substrate holder with the photodiodes facing upwards.
2. Start the Solar Cell I-V software and enter the following settings:

Figure 9.18. Measurement Settings for the solar characterisation and lifetime measurements: Screenshot of Measurement Settings, similar to Figure 9.7, with specific values for taking a measurement.

The other settings can be left as default.

3. Place the test system under a solar simulator and select ‘Measure'. The system should record the classic diode response (no response for negative bias and exponentially increasing current for increasing positive bias). The test can also be performed without the use of a solar simulator, however the current density will not be shifted below zero.

Figure 9.19. Software settings and photodiode response: Screenshot showing software settings and the resulting photodiode response graph.

10. Troubleshooting

Most of the issues that may arise will be detailed here. However, if you encounter any issues that are not listed here, then contact Ossila by email at info@ossila.com. Ossila will respond as soon as possible.

11. Related Products

11.1 Related Consumables

• ITO Substrates: Our range of 15 x 20 mm ITO substrates for OPV, OLED and sensing applications. Product codes: S111 / S101 / S211 / S281 / S171
• FTO Coated Glass Substrates: Designed to be used in the fabrication of transparent electrodes for thin-film photovoltaics. Product code: S301 / S302 / S303 / S304
• Flat tip tweezers: Provides a good substrate grip without scratching. Product codes: C121
• Substrate Cleaning Rack: Holds 20 substrates for a variety of processing techniques. Product code: E101

11.2 Related Equipment

• Spin Coater: Produce high-quality coatings without any substrate warping. Perfect for busy labs with limited space. Product code: L2001A3
• UV Ozone Cleaner: For removing contamination on the surface of samples, providing you with ultraclean surfaces within minutes. Product code: L2002A2
• Syringe Pump: High-precision, programmable single and dual syringe pumps for the automatic dispensing of solutions. Product codes: L2003S1 / L2003D1
• Source Measure Unit: Source voltage, measure current, get data. Simplify and accelerate your data collection! Product code: P2005A2

Back Matter

The document includes logos for 'The Queen's Awards for Enterprise: International Trade 2018' and 'Innovation Award 2017 IOP Institute of Physics'.

Copyright © Ossila 2020

Website: Ossila.com