Engineering Quantum Photocells through Donor Multiplicity: Scaling Photocurrent and Power with N-Donor Architectures
Scaling quantum photovoltaic architectures beyond a few interacting molecular units remains a fundamental challenge for understanding how collective quantum dynamics translate into macroscopic electrical output. We present a scalable quantum photocell architecture consisting of N identical donor molecules symmetrically arranged around a central acceptor, extending previous two- and three-donor models. Treating the system as a quantum heat engine and solving the Born-Markov master equation, we systematically compare the uncoupled and coupled regimes. Intermolecular coherent coupling produces delocalized collective excitonic states and modifies the excitation transfer dynamics relative to independent donors. As the number of donors increases, both the steady-state photocurrent and output power increase sublinearly, with the coupled network consistently outperforming its uncoupled counterpart for every N examined. The open-circuit voltage remains essentially unchanged, indicating that the power enhancement does not arise from an increase in the voltage output, but rather from modified excitation and charge-transfer dynamics. These results identify donor multiplicity, together with coherent intermolecular coupling, as complementary design parameters for engineering scalable quantum photovoltaic systems, and demonstrate that collective excitation dynamics can provide an intrinsic route to enhanced power generation beyond the additive contribution of independent molecular absorbers.