Fig. 4.

Electrically driven single-molecule single-photon emission. a STML spectra acquired at different sample sites using the same tip: ZnPc-lobe/4 ML NaCl, ZnPc-lobe/3 ML NaCl, and 4 ML NaCl, respectively (−2.5 V, 100 pA, 30 s). The inset of a shows the STM image of isolated ZnPc molecules on 3 and 4 ML NaCl (2.5 V, 2 pA, 16 × 6 nm²). The spectra are offset for clarity. b Second-order correlation measurements of single-molecule electroluminescence at the molecular lobe of a ZnPc (−2.5 V, 100 pA) and NaCl (−2.5 V, 500 pA), corresponding to the STML spectra in a, respectively. The black, red, and blue lines are the single exponential fit to the data. The upper curves have been upshifted by multiples of one for clarity. c Consecutive STML spectra acquired every 5 min during second-order correlation measurements at the ZnPc lobe on 4 ML NaCl (−2.5 V, 100 pA, 60 s). The yellow areas marked in a, c indicate the detection range of the band-pass filters used in the present experiments (1.872–1.915 eV). d Short-time trace of STML spectra (−2.5 V, 100 pA, 1 s for each spectrum) and intensities (detected by SPAD at a sampling rate of 50 Hz) when the tip is positioned at the ZnPc molecular lobe on 4 ML NaCl