The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly(p-phenylene vinylene) chains in the framework of the tight-binding approach.We obtain an intrachain exciton and biexciton as well as an interchain exciton and biexciton through a double-photon excitation.It is found that a biexciton is energetically favourable to two single excitons even when there exists an interchain coupling.There is a turnover value t ⊥C of the interchain coupling for the formation of a biexciton,beyond which two excitons are combined into one biexciton.The binding energy of a biexciton is calculated to decrease with the increase of interchain coupling,which indicates that a biexciton is relatively stable in polymers with a weak interchain coupling.The conclusion is consistent with the experimental observations.In addition,a suggestion about how to improve the yielding efficiency or the formation of biexcitons in actual applications is given. The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly (p-phenylene vinylene) chains in the framework of the tight-binding approach. We obtained an intrachain exciton and biexciton as well as an interchain exciton and biexciton through a double-photon excitation. It is found that a biexciton is energetically favourable to two single excitons even when there exists an interchain coupling. There is a turnover value t ⊥ C of the interchain coupling for the formation of a biexciton, which two excitons are combined into one biexciton. the binding energy of a biexciton is calculated to decrease with the increase of interchain coupling, which indicates that a biexciton is relatively stable in polymers with a weak interchain coupling. the conclusion is consistent with the experimental observations. addition, a suggestion about how to improve the yielding efficiency or the formation of biexcitons in actual applications is given.