In the case of a photovoltaic cell, minority carrier-lifetime is an important parameter in determining the overall performance. The conventional method, namely time-resolved photoluminescence, is not perceived as a foolproof technique in calculating the above parameter given the high surface recombination, particularly in thin-film (polycrystalline) solar cell. Consequently, many researchers employ the two-photon excitation measurement technique as an alternative.
My enquiry is about the theoretical understanding and methodology of the above procedure.
Dear Bazlul Karim ,
welcome!
Th two photo excitation is thought to generate electron hole pairs by photons simultaneously on the materials. The two photons will be absorbed simultaneously and generate an electron hole pair. The most important thing is that the two photons have larger wavelength than the one photon method such that they can penetrate deeper in the volume of the material far from the surface.
Therefore they will recombine in the volume rather than in the surface orf near the surface as the one more energetic photons.
In both cases the one measures the life time by the photoconductive decay.
For the photoconductive decency experiment please follow the references:Method Measuring the semiconductor parameters
For the generation of the two photons and applying it to measure the bulk lifetime please follow the reference:https://www.nature.com/articles/srep02098
Best wishes
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