Fig. 3: Statistical study of single terrylene molecules on annealed and non-annealed hBN.

a 0-0 zero-phonon line (ZPL) positions of 373 terrylene molecules divided into sets of two colors. The blue points (123 molecules) represent 0-0 ZPL positions on non-annealed hBN flakes, while the red points (250 molecules) correspond to flakes subject to annealing with at least 500 °C and for some samples up to 900 °C. After annealing, a small and narrower distribution of 17 molecules is found around 602 nm with some additional molecules between 582 nm and 602 nm. b Shows the measured relative intensity of the main vibration (0-1 ZPL) versus the position of the 0-0 ZPL for 58 molecules on non-annealed hBN (blue points) and 113 molecules on annealed hBN (red points). On average, the more red-shifted molecules have a weaker vibronic coupling (Pearson’s correlation coefficient r = −0.56). For the same set of molecules, a less-significant relation (r = 0.4) is found for the vibration energy compared to the 0-0 ZPL position in (c). The statistics in (a) are higher than for (b, c) because the ratio and energy of the vibrational peaks were not always clearly resolved in the spectra due to overlap with other molecules.