Thesis defence E.M. Hutter: perovskites

19 June 2018 12:30 - Location: Aula, TU Delft - By: webredactie

Revealing the Fate of PhotoGenerated Charges in Metal Halide Perovskites. Promotor: Prof.dr. L.D.A. Siebbeles (TNW).

In less than a decade of development, metal halide perovskites (MHPs) have yielded solar cells with efficiencies exceeding 20%, which is comparable to commercialized technologies. In this research, we aim to understand which factors are currently limiting the performance of MHP-based solar cells and how the efficiencies could be further improved. One of the crucial processes in a solar cell is the conversion of absorbed light into a current of moving charges. To reveal the fate of these moving charges in MHPs, we used a number of spectroscopy techniques, with which we shortly illuminate the MHPs and, thereby mimicking the processes occurring in a solar cell.

One of our findings described in this thesis is that moving charges can get immobilized in the MHP layer itself or at the interface between the MHP and the material that is supposed to extract the charges in a solar cell. This impedes the collection of charges and hence, lowers the efficiency. Therefore, to obtain more efficient MHP-based solar cells, the quality of the interfaces should be substantially improved. One of our most important conclusions however is that moving charges encounter a barrier for recombination, which makes it more likely for the charges to be collected. Hereby, we have found a unique property of MHPs.

Finally, we have investigated whether the toxic component lead, which is present in MHP-based solar cells, could be replaced with less toxic metals, while preserving the favorable properties of lead-based MHPs. From our measurements, we find that MHPs based on a mixture of silver, bismuth and antimony, are a promising alternative for lead-free MHP-based solar cell. 

More information?

For access to theses by the PhD students you can have a look in TU Delft Repository, the digital storage of publications of TU Delft. Theses will be available within a few weeks after the actual thesis defence.