Computational design of donor-acceptor stacked polycyclic aromatic hydrocarbons as photocatalytic sites in carbon...

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.