Plotting the IV Curve of a Solar Cell in EChem Software
Plotting the IV Curve of a Solar Cell in EChem Software
This application note describes a procedure for plotting the IV curve of a solar cell using eDAQ EChem software.
Introduction The linear sweep voltammetry technique in EChem software can be used to plot the IV curve of a solar cell. The software can then overlay many IV curves recorded under different conditions. The EChem Startup System is an inexpensive, easy to use system for characterising solar cells.
Equipment Required The following equipment is required: Computer with EChem and Chart softwares installed ER466 Potentiostat, or e-corder with EA163 potentiostat ET325 Thin film solar cell
Procedure To plot an IV curve in EChem software, start by determining the open circuit potential of the solar cell: Connect the electrodes cable of the potentiostat to the solar cell as follows: working electrode (green clip) on one side of the solar cell and auxiliary electrode (red clip) on the other side. Do not connect the reference electrode (yellow clip) to the solar cell at this time. Open the Chart software and use the High Z mode (High Impedance Voltmeter) of the potentiostat. Open the potentiostat window, select Mode = High Z, Range = 10 V and Cell = Real. The voltage can be read in the top left side of the window. This voltage is the open circuit potential of the solar cell, the voltage across the solar cell when no current is flowing. Please see the “Potentiostat, Picostat and QuadStat manual” for more information about this. If you are using a potentiostat which doesn't have High Z mode, use either a pH meter in voltage mode, or a voltmeter, to measure the open circuit potential of the solar cell. Make a note of the open circuit potential and close the Chart software. Now connect the electrodes cable of the potentiostat to the solar cell as follows: working electrode (green clip) on one side of the solar cell and auxiliary and reference electrodes (red and yellow clips) on the other side. Open the EChem software and in the Technique menu chose “Linear Sweep”. Select a voltage range which is higher than the open circuit potential. Enter the value of the open circuit potential in “Initial” and zero in “Final”. Chose an appropriate rate. Click View to see how long the sweep will take. Click OK. Click Start to perform a scan. Expand the y-axis (current) to see the maximum current recorded. Change the current range of the potentiostat; the range must be higher than the maximum current, otherwise you will lose data points. Click Start to repeat the scan using the new current range setting. Check to see if the current reaches zero in the bottom right of the IV curve; if the current is always positive and never reached zero, you must increase the “initial” value in the Linear sweep window; if the current falls a lot below zero, do the opposite by decreasing the “initial” value, as this may damage your solar cell.
You can easily copy and paste the voltage and current values, or the IV picture, into third party software using the menu Edit, then Copy Special. Select the menu Display, then “Show Overlay” to overlay the IV curves you have collected; if you would like to delete a scan, select the menu Edit, then Cut.
