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Incident photon-to-current efficiency measurement system

Straathof, N.M. (2012) Incident photon-to-current efficiency measurement system.

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Abstract:A system has been designed that is able to measure the quantum efficiency of solar cells. This has been done by first filtering the light of a light source so only one wavelength can pass. Next, the beam will be split in two separate beams, whose intensities will be measured by a reference detector and a sample cell. When doing this for all wavelengths and comparing these measurements, the quantum efficiency can be calculated for every wavelength. This project has been divided in two parts. The first part is about designing a system capable of measuring the quantum efficiency. The second part is to write a program that is capable of performing this measurement fully automatically and that is able to be used by users inexperienced with the program Labview. A sensor system has been designed to measure the beginning and end position of the monochromator. This is a device that filters all wavelengths, except one. Because it has a beginning and end, the sensor system has been designed to measure these points, so the stepper motor that controls the monochromator will not damage the monochromator. Also equipment has been designed to able the user to mount an optic filter in front of the monochromator, to prevent contaminating light from lower wavelength in the measurement. In Labview a program has been written that is able to measure the quantum efficiency fully automatically. It gives the user the possibility to enter the boundary conditions of the measurement, for example the wavelength range, the measurement time and the dark current of the sample cell. The program is also able to use the components separately; the stepper motor can be put in a wanted wavelength position, the current of the reference detector can be measured and with the multimeter the voltage and current can be measured. At last some tests have been done to check the performance of the system. It appears the system can give a good indication of the quantum efficiency for wavelengths between 500 and 680 nm. However, below and above this range the system is not accurate due to low light intensity. This is why it is advisable to change the light source with one that emits a broader range. This will allow the user to perform more accurate measurements on a broader range. Also the fact that the used reference detector is not calibrated causes inaccuracy.
Item Type:Internship Report (Master)
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Link to this item:http://purl.utwente.nl/essays/64631
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