Fig. 3
From: Ultralong UV/mechano-excited room temperature phosphorescence from purely organic cluster excitons
Photoluminescence (PL) properties of the guest/host system. a Steady-state and delayed PL spectra of NA/PCP (λex = 254 nm) at ambient conditions. Insert: photos of NA/PCP under 254 nm UV light irradiation and after UV irradiation ceased for different times. b, c are the same as (a) except that NA/PA and NA/DCB were used, respectively, instead of NA/PCP. For delayed spectra in (b, c), Δt = 50 ms. d Time-resolved decay curves of NA/PCP, NA/PA, and NA/DCB at maximum phosphorescence emission (λex = 254 nm) and at maximum fluorescence emission (insert, λex = 280 nm) at ambient conditions. NA/PCP, NA/PA and NA/DCB were obtained using a melt-casting method with a starting mass ratio of NA: PCP = NA: PA = NA: DCB = 1:100, respectively. Melt-casting: heat up to the melting point (Tm) of the host to dissolve NA as colorless and clear solution, then cool to room temperature quickly. Tm(PCP) = 126 °C; Tm(PA) = 131 °C; Tm(DCB) = 139 °C. ϕ(F + P): overall quantum yield; τF: fluorescence lifetime; τP: phosphorescence lifetime
