AbstractThe influence of photon recycling (PR) onto the minority carrier distribution in double heterostructures is investigated. For non‐perfect optical confinement of the luminescence radiation in the active zone, the corresponding integro‐differential equation (without drift term) of the diffusion model cannot longer be solved exactly. The enlargement of the radiative lifetime, as measured in photoluminescence experiments, e.g., is calculated approximatively by means of perturbational methods. Particular attention is devoted to the dependence of this enlargement due to PR upon the thickness of the active zone. In very thin active zones, PR should play a minor role due to the loss of luminescence radiat