Radiative Relaxation in Luminescent Silicon Nanocrystal Thiol-Ene Composites

Abstract

Efficient photoluminescence (PL) from silicon nanocrystal (SiNC) composites has important implications for emerging solar-collection technologies, yet a detailed understanding of the landscape of PL relaxation in vitrified colloidal SiNCs is still materializing. Here, we explore details of PL relaxation in photo-polymerized off-stoichiometric polymer/nanocrystal hybrids. Specifically, thiol-ene polymer/nanocrystal composites were synthesized from a tetra-functional thiol, tri-functional allyl, and a family of dodecyl-passivated colloidal SiNCs with peak PL wavelength spanning 700–950 nm. We find time- and air-stable emission from dilute composites with up to 70% quantum yield, and we investigate PL relaxation in the parameter space of nanocrystal size and temperature, focusing on changes in the partitioning of multimodal decay upon going from the colloid to composite. In light of previous work, our results reveal similarities between the impacts of crosslinking and cooling to cryogenic temperatures, both of which are characterized by a relative reduction in the availability of phonons.