Production and luminescent properties of CdSe and CdS nanoparticle–polymer composites

New polymers with pendant phosphine or phosphine oxide groups are prepared by catalytic hydrosilation of polybutadienes and subsequent elaboration. The polymers are used to control the reaction of Me2Cd with H2Se to give nanoparticles, for which the size can be controlled by using different reaction times. Composite films can be cast directly from the reaction solutions. The role of the polymer and the phosphine groups in controlling the particle growth is discussed. Luminescence studies show that the larger nanoparticles demonstrate near band-edge luminescence, but for smaller particles the energy and profile of the emission band (quantum yield up to ca. 45%) is independent of the particle size. This size-independent luminescence is broad and approximates to white light. The possible role of polymeric states in the generation of this luminescence is discussed. Blue emission can be obtained from similar composites, but containing CdS in place of CdSe. This blue luminescence is quenched by air, but irradiation with blue light regenerates a broad orange emission associated with surface states on the particles.