A chemist is designing an organic photovoltaic (OPV) cell. Which factor primarily determines the open-circuit voltage of this OPV cell?

💡 Explanation

The open-circuit voltage (Voc) in an OPV cell is directly related to the energy difference between the highest occupied molecular orbital (HOMO) of the donor and the lowest unoccupied molecular orbital (LUMO) of the acceptor material at the donor-acceptor interface. This energy difference arises because the electronegativity difference influences the energy levels. Therefore, the electronegativity difference dictates the Voc, rather than the polymer chain length, surface roughness or solvent evaporation rates.

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