Resonance energy transfer between polar charge-transfer dyes: A focus on the limits of the dipolar approximation

► Resonance energy transfer (RET) between pairs of polar dyes is investigated. ► The limits of the dipolar approximation for the description of RET are discussed. ► Essential-state models are adopted to describe electrostatic interactions for RET. ► Results from essential-state models are in good agreement with TDDFT calculations.