Ultra Efficient Quantum Ratchet Solar Cells

Lead Research Organisation: Imperial College London
Department Name: Physics


The efficiency of a solar cell can be significantly augmented if sequential
absorption of photons can be achieved. This can both increase the spectral
range over which a solar cell can absorb and reduce the quantity of energy
lost as parasitic heat generation within the solar cell. We have recently
proposed a means by which sequential absorption can be promoted in
semiconductor quantum heterostructures . The PhD project aims to
demonstrate this new type of solar cell experimentally.
M. Yoshida, N. J. Ekins-Daukes, D. J. Farrell, and C. C. Phillips, Applied Physics Letters 100, 263902 (2012).
Okada, Y. et al., Intermediate band solar cells: Recent progress and future directions. Applied Physics Reviews, 2(2), p.021302.( 2015)
Curtin, O.J. et al.,Photovoltaics, IEEE Journal of, 6(3), pp.673-678.(2016)
Pusch, A. et al.. Progress in Photovoltaics Research and Applications
, 24(5), pp.656 (2016)


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509486/1 01/10/2016 31/03/2022
1992406 Studentship EP/N509486/1 01/10/2017 30/09/2021 Kenneth Hughes
Description The device discussed in the previous report has now been shown to absorb two sub-bandgap photons for sequential absorption and generation of an electric current. The details of its behaviour still need to be fully analysed in order to properly compare this device to the previous one. What can be said already is that the device still only works at very low temperatures (best below ~20K), and so this design is still not appropriate for real-world use. The structural changes were not made with this in mind, however, so this is not a failure of the device. This sample was made to operate at a higher intensity of one of the incident light beams; the relative success or failure of this has yet to be determined, but simply requires some analysis of the data that has been acquired.

A second device is now being investigated, and its design includes a feature that is targeted at this poor high-temperature operation. Thus far it has been shown to exhibit the same plateau in the one-photon photocurrent as other devices, and indeed this behaviour exists even at room temperature, which is promising.
Exploitation Route The data acquired heretofore must be analysed so that the true impact of the structural changes can be quantified. Further data are then to be acquired from other sample designs, and the relative successes of each determined. Based on these, further refinements can be made and designs submitted for fabrication, taking these devices closer to the end goal of a viable, working ultra-efficient solar cell.
Sectors Energy,Environment