Light quenching of photoluminescence in hybrid films of InP/InAsP/InP nanowires and CdSe/ZnS colloidal quantum dots

Abstract

We investigate the photoluminescence of a film obtained by the uniform deposition of a colloidal solution of CdSe/ZnS quantum dots capped by trioctylphosphine oxide on an array of isolated InP/InAsP/InP nanowires and subsequently removed from the substrate. The photoluminescence spectrum of the film shows emission bands corresponding to InAsP nano-insertions (1.25–1.5 μm) and quantum wells (1.0–1.2 μm). We find that the dependence of the photoluminescence intensity on the excitation intensity has a nonlinear character, which we interpret as a manifestation of the light quenching effect, and that the photodynamics of excitation of the nano-insertions and quantum wells differ from each other. We analyse the light quenching effect taking into account the significant increase in the luminescence intensity observed in such hybrid film as compared to an array of isolated InP/InAsP/InP nanowires. We hypothesize the possible suppression of Auger relaxation due to multistep nonradiative transfer of excitation.