Many‐exciton effects in the theory of biexcitons

Starting from a previously derived many‐particle equation describing biexciton states, dynamical screening effects in the irreducible exciton‐exciton interaction are taken into account. As a result, density‐dependent biexciton binding energies are obtained. Numerical results are given for CuCl and CuBr in the region of free‐exciton density from 10−5 ≦ nexa ≦ 5 × 10−2. In qualitative agreement with experimental data only a small shift of the biexciton luminescence line should be observed.