Metal halide perovskite cells have shown very high efficiencies before, but there have always been a load of problems with them that have made them unsuitable f

Metal halide perovskite cells have shown very high efficiencies before, but there have always been a load of problems with them that have made them unsuitable for large scale production. They are very sensitive to discrepancies in deposition thickness on the substrate. This means you can spin coat very small cells in a lab, but applications on larger substrates always gives a massive decrease in efficiency. I see this paper talks about cells with an area of 1cm^2, so presumably this problem is still not overcome.