Fig. 3. Photoluminescence of C-centred gold(I) clusters in the solid state and the theoretical study.

a Emission spectra: SS-1^NHC (blue line, excited by 266 nm), SS-2^NHC (orange line, excited by 510 nm), 1^TPP (blue line, excited by 356 nm), 2^TPP (yellow line, excited by 365 nm), insets: photographs (size: 12 mm ×12 mm) of crystals under 365 nm UV-light irradiation. b The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) distributions of SS-2^NHC. c HOMO–LUMO gap values based on theoretical calculations: SS-1^NHC (3.99 eV), SS-2^NHC (3.30 eV), 1^TPP (4.50 eV), and 2^TPP (3.98 eV). Source data are provided as a Source Data file.