Further insight into the environmental factors is gained from photoluminescence lifetimes. TCNQ (C 1 peak) has been resonantly excited at 405 nm. See the results for DCTC -(C 2 peak) measured at 470 nm in the SI, section S4. Figure shows the decay curves for TCNQ (C 1 ) in single crystals of doped melamine prepared with mole percentages of TCNQ to melamine of 0.04 % (Crystal 1) and 1.25 % (Crystal 5), and the decay curves for the respective precursor aqueous THF solutions, measured at a laser wavelength of 405 nm and an emission band path of 425 -455 nm. All the curves can be fit with triple exponential functions. Lifetimes and relative amplitudes evaluated for different 0.04 % crystals are plotted in panel h, and for 1.25 % crystals in panel i. In both 0.04 % and 1.25 % crystals, dominant fluorescence lifetimes are approximately 2 ns which is much slower than about 0.14 ns estimated for the precursor solutions. The much delayed fluorescence is apparently because of the solid state environment in which fluorescent molecules are immobilized in a crystal of melamine, and the passivation of non-radiative decay processes, e.g. fast (ps -fs) internal conversion , allows TCNQ to luminesce.