Computational design of donor–acceptor stacked polycyclic aromatic hydrocarbons as photocatalytic sites in carbon dots

Abstract

Carbon dots (CDs) are complex carbon-based nanomaterials with exceptional photoluminescence characteristics and great promise for sustainable metal-free photocatalysis. However, their structural heterogeneity poses a major challenge for the rational design and prediction of photocatalytic performance. To overcome this limitation, we propose a bottom-up strategy centered on CD-inspired systems with well-defined molecular architecture. Specifically, we computationally screened 5700 stacked polycyclic aromatic hydrocarbon aggregates, as representatives of CD aromatic domains, to identify donor–acceptor pairs capable of efficient charge separation under photoexcitation. Using a few carefully chosen molecular descriptors and a computationally efficient protocol, we identified best candidate systems for oxidative and reductive quenching pathways. Subsequent time-dependent density functional theory analysis confirmed that these systems exhibit key photocatalytic features: a charge-transfer character in the lowest excited state, well-separated bright local excitations, favorable redox potentials, and propensity for extended aggregation with core-surface charge separation. Our approach not only offers a practical design route for CD-like photocatalysts but also provides the fundamental understanding needed to engineer tunable, efficient, and sustainable donor–acceptor photocatalytic systems.