Fig. 1. (a) Chemical structures of the template and target compounds. (b) The normalized UV-vis absorption and PL spectra of HPJP and DHN-DJP in DCM solutions.

Fig. 2. (a) Diagram of the ESDPT process in DHNs. (b) Calculated relative energies (kcal/mol) on S₀ and S₁ of DHN-DMP in vacuum.

Fig. 3. (a, c, e) The normalized UV‒vis absorption and PL spectra of DMN- and DHN-doped PS films. (b, d, f) The decay plots and fitted curves of DHNs.

Fig. 4. (a) Schematic diagram of a single DHN-doped microsphere. (b) PL micrograph of a single DHN-doped microsphere. Inset: scanning electron microscopy image of a single DHN-doped microsphere. (c) Partial magnifications of PL spectra of DHN-doped microspheres with different sizes. (d) The related curve of λ²/Δλ (λ: emission wavelength; Δλ: the space between the individual resonance peaks) at 700 nm versus D (D: diameter of selected microsphere). Inset: the simulated electric energy density in the cross-section of a microsphere with dimeter D = 10 µm. Red corresponds to the highest field density and blue is the lowest field density.

Fig. 5. PL spectra of (a) DHN-DMP-, (d) DHN-DPP- and (g) DHN-DJP-doped PS microspheres under different pump densities. (b) Plots of lasing intensity as a function of pump density of a (b) DHN-DMP-, (e) DHN-DPP- and (h) DHN-DJP-doped PS microsphere. Insets: brightfield micrographs of the PS microspheres used in laser measurements. (c) 2D mappings of lasing intensity versus the number of pulses of a (c) DHN-DMP-, (f) DHN-DPP- and (i) DHN-DJP-doped PS microsphere, pumping density: 47.8 µJ/cm².