How to Measure and Calculate Band Gap of a Photovoltaic Device

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Discussion Overview

The discussion revolves around measuring and calculating the band gap of a photovoltaic device, specifically at temperatures of 300 K and 0 K. Participants explore methods for measurement and calculation, including the use of monochromatic light and temperature data.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using monochromatic light to determine the band gap voltage based on the maximum wavelength that generates current, referencing the relationship between photon energy and wavelength.
  • Another participant expresses difficulty in obtaining monochromatic light and inquires about alternative methods, mentioning their testing of the device with temperature.
  • A further contribution proposes assuming a black-body spectral distribution from the light source, suggesting that as temperature increases, the output current should reflect the interaction between blackbody radiation and the diode's spectral response.
  • This participant notes that a correlation calculation could be used to model the diode response based on temperature data, although they caution that results may be imprecise and dependent on experimental setup and modeling assumptions.
  • One participant humorously suggests contacting the manufacturer for assistance.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method for measuring the band gap, with multiple competing views and approaches presented throughout the discussion.

Contextual Notes

Participants mention limitations such as the availability of monochromatic light and the need for a good experimental setup, as well as the potential for imprecise results due to modeling assumptions.

tornado
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Hi there!

I bought a photovoltaic cell. I would like to learn its band gap at 300 K and 0 K. How can i measure band gap or calculate? I have already measured Temperature to Vmax values.

I couldn't find any good information about this topic.

Thanks.
 
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Thank you so much! But i can't find a monochromatic light. Is there any different option? I tested this device with temperature. Its like a thermophotovoltaic.
 
tornado said:
Thank you so much! But i can't find a monochromatic light. Is there any different option? I tested this device with temperature. Its like a thermophotovoltaic.
Interesting, the first time I ever heard of these things.

It seems you can assume a black-body spectral distribution from the source. As the temperature is increased there will be an output current that should be the product of the two transfer functions; blackbody radiation times diode spectral response. With enough temperature data points I would think you could do something like a correlation calculation to model the diode response required to match the data. As the temperature is increased, you should see a current increase that is more rapid than the blackbody distribution could explain, this would be from the diode "turning on". However, you would need a good experimental setup and some modelling assumptions, and then you still might get a pretty sloppy result.

How about just calling the manufacturer and asking?
 

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