Time-resolved spectroscopy of oligomerized phenyl modified carbon nitride

Polymeric graphitic carbon nitride (g-CN), as one of the simplest organic semiconductors, has been extensively exploited for applications in fields from optoelectronics to energy. The photophysics of the g-CN and their different monomers have been well established, while the oligomerized counterparts have been rarely explored, in spite of its better dispersity in solvent and uncompromised optical properties. To fill this gap, here we examine the photophysics of oligomerized variants obtained by condensation of a model compound benzoguanamine. Steady-state spectra reveals a slightly blue-shifted emission peak at 500 nm of the oligomer mixtures with enhanced photoluminescence (PL) quantum yield as compared with g-CN. From time-resolved PL spectra, this emission band exhibits a characteristic fast decay time of approximately 10 ns and the decay of PL is synchronized with the decay of photon-induced absorption from an excited state of spin-singlet character. The transient spectra also unravel a long-lived state with characteristic life time of over 100 ns, which is suggested to be associated with the trap states. The results of the present work suggest that oligomers with suppressed trap formation could be strong alternatives for g-CN used in diverse photonics applications.

Automated summary

The photophysics of oligomerized variants obtained by condensation of a model compound benzoguanamine were examined, revealing higher photoluminescence quantum yield and a slightly blue-shifted emission peak at 500 nm compared with g-CN. The results suggest that oligomers with suppressed trap formation could be strong alternatives for diverse photonics applications.