Nanoclusters in organic-inorganic hybrid bismuth halide can be used for the splitting of a high-energy photons and this could bring advances in solar cells as they are arranged in a bulk crystalline material that can be processed from solution. The generation of two low-energy photons from a high-energy one has been observed in quantum dots and lanthanide ions due to the confinement of excitons and the transport of charge carriers from neighbouring ones (Nature Communications 8, 2017, 170).