The upconversion of photons allows for a more efficient use of light: Two photons are converted into a single photon having higher energy. Researchers at KIT now showed for the first time that the inner interfaces between surface-mounted metal-organic frameworks (SURMOFs) are suited perfectly for this purpose - they turned green light blue. The result, which is now being published in the Advanced Materialsjournal, opens up new opportunities for optoelectronic applications such as solar cells or LEDs. (DOI: 10.1002/adma.201601718)