biostudies-literatureSmit RDutch Research Council (NWO)7960https://www.ebi.ac.uk/biostudies/studies/S-EPMC10693553biostudies-literatureUnknown14(1)Single fluorescent molecules embedded in the bulk of host crystals have proven to be sensitive probes of the dynamics in their nano environment, thanks to their narrow (about 30-50 MHz or 0.1-0.2 μeV) optical linewidth of the 0-0 zero-phonon line (0-0 ZPL) at cryogenic temperatures. However, the optical linewidths of the 0-0 ZPL have been found to increase dramatically as the single molecules are located closer to a surface or interface, while no 0-0 ZPL has been detected for single molecules on any surface. Here we study single terrylene molecules adsorbed on the surface of hexagonal boron-nitride (hBN) substrates. Our low-temperature results show that it is possible to observe the 0-0 ZPL of fluorescent molecules on a surface. We compare our results for molecules deposited on the surfaces of annealed and non-annealed hBN flakes and we see a marked improvement in the spectral stability of the emitters after annealing.Nature communicationsSharp zero-phonon lines of single organic molecules on a hexagonal boron-nitride surface.PMC10693553Spinoza premie OrritSmit RTebyani Avan der Molen SJOrrit MHameury JfalseSharp zero-phonon lines of single organic molecules on a hexagonal boron-nitride surface.Single fluorescent molecules embedded in the bulk of host crystals have proven to be sensitive probes of the dynamics in their nano environment, thanks to their narrow (about 30-50 MHz or 0.1-0.2 μeV) optical linewidth of the 0-0 zero-phonon line (0-0 ZPL) at cryogenic temperatures. However, the optical linewidths of the 0-0 ZPL have been found to increase dramatically as the single molecules are located closer to a surface or interface, while no 0-0 ZPL has been detected for single molecules on any surface. Here we study single terrylene molecules adsorbed on the surface of hexagonal boron-nitride (hBN) substrates. Our low-temperature results show that it is possible to observe the 0-0 ZPL of fluorescent molecules on a surface. We compare our results for molecules deposited on the surfaces of annealed and non-annealed hBN flakes and we see a marked improvement in the spectral stability of the emitters after annealing.2023-01-01T00:00:00Z2023 Dec2025-05-29T21:46:51.11Z2025-02-19T01:17:27.058ZS-EPMC106935533804282610.1038/s41467-023-42865-4