How to Measure and Calculate Band Gap of a Photovoltaic Device

[tornado]

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.

 

[Baluncore]

The maximum wavelength light that will generate a current is determined by the PV cell band gap voltage. (There is some thermal broadening). So illuminate it with monochromatic light. As the photon wavelength is reduced and photon energy rises, there will be a point where the PV cell begins to generate current.

Energy in eV = 1239.84 / λ nm = band gap voltage.

https://en.wikipedia.org/wiki/Photon_energy
https://en.wikipedia.org/wiki/Planck–Einstein_relation

 

[tornado]

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.

 

[DaveE]

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?