Perovskite cells: Researchers improve understanding of tolerance to defects

Researchers at the University of Cambridge have illustrated why perovskite cells are relatively tolerant of defects in their structure. Unlike crystalline silicon, perovskites do not have a highly ordered crystal lattice typical of semiconductors, but rather a more disordered structure – or »messier landscape«, as the researchers from Cambridge’s Department of Chemical Engineering and Biotechnology (CEB) call it. The defects in the material lead to tiny traps for electrons, which should normally reduce performance. Nevertheless, pure perovskite cells are now approaching the efficiencies of silicon cells. Previous research by the same team behind the current work has shown that the disordered structure can actually increase the performance of perovskites.
By combining a number of new microscopy techniques, the team led by CEB’s Kyle Frohna has now achieved a better understanding of what happens in perovskites. »What we see is that we have two forms of disorder happening in parallel,« Frohna said. »And what we’ve found is that the chemical disorder – the ›good‹ disorder in this case – mitigates the ›bad‹ disorder from the defects by funnelling the charge carriers away from these traps that they might otherwise get caught in.« The findings have now been published in the journal Nature Nanotechnology.
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