Triplet Excitons in Carbon Nitride Materials: From Melem Monomers to Extended Polymers

TL;DR

This paper investigates how triplet excitons behave in carbon nitride materials, showing that polymerization affects their delocalization.

Contribution

The study directly probes triplet exciton delocalization in carbon nitride materials using TR-EPR spectroscopy.

Findings

Fully polymerized CN frameworks sustain strongly delocalized triplet excitons.

Localized triplet exciton states are observed in incompletely condensed CN structures.

Network polymerization is linked to exciton delocalization and photocatalytic processes.

Abstract

Owing to their earth-abundant constituents and tunable
electronic
structure, Carbon Nitride (CN) materials have emerged as a versatile
class of photocatalytic systems. Their photocatalytic activity is
linked to a complex excited-state landscape, where the role of triplet
excitons remains under debate. In this work, we use time-resolved
electron paramagnetic resonance (TR-EPR) spectroscopy to directly
probe the spatial extent of triplet excitons as a function of the
degree of thermal polymerization. We find that fully polymerized CN
frameworks sustain strongly delocalized triplet excitons, in contrast
to the localized states observed in incompletely condensed structures
containing molecular or oligomeric units. These results establish
a clear connection between network polymerization and exciton delocalization,
providing mechanistic insight into the photophysical processes that
govern charge separation and reactivity in CN-based photocatalysts.

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