This work is devoted to studying the features of the optical properties of self-catalyzed axially heterostructured GaNP/GaP nanowires on Si(111) grown by plasma-assisted molecular beam epitaxy. Transparent polydimethylsiloxane rubber was used to determine the photoluminescent properties of the grown NW arrays and the parasitic layer separately. Low-temperature photoluminescence studies demonstrate the transition to a quasi-direct bandgap in nanowires, which is characteristic feature of diluted nitrides with a low nitrogen content. The bright photoluminescent response at room temperature demonstrates the potential application of nanowires/rubber membranes in flexible optoelectronic devices. #COMESYSO1120.