Magneto-optical absorption of quantum wells exhibits distinct excitonic res
onances and allows the determination of exciton binding energies and diamag
netic shifts. Here, we report a magneto-absorption study on Zn0.69Cd0.31Se/
ZnSe multiple quantum wells 4 and 5 nm thick yielding 1S exciton binding-en
ergy values. These results are compared to calculations based on two theore
tical models that include the exciton-phonon interaction potential or the s
creened Coulomb potential. This analysis allows us to discriminate between
the two models and highlights for the first time the impact of polaronic co
upling on the optical behavior of these polar heterostructures.