Synthesis of Luminescent Thin-Film CdSe/ZnSe Quantum Dot Composites Using CdSe Quantum Dots Passivated with an Overlayer of ZnSe

Electronic and chemical passivation of CdSe nanocrystals (quantum dots) has been achieved with a thin ZnSe overlayer grown in solution from trioctylphosphine selenide and diethylzinc. Layered particles with a [ZnSe/CdSe] ratio ranging from 0 to ∼5.0 were prepared and characterized by optical absorption spectroscopy, photoluminescence, high-resolution transmission electron microscopy, Auger electron spectroscopy, and X-ray scattering. The overgrown particles were crystalline and displayed band-edge absorption and emission characteristic of the initial CdSe nuclei. Thin-film quantum dot composites incorporating bare and overcoated CdSe nanocrystals in a ZnSe matrix were synthesized by electrospray organometallic chemical vapor deposition (ES-OMCVD). The photoluminescence spectra of the composites with bare CdSe dots were dominated by broad deep-level emission and the photoluminescence yield deteriorated with increasing deposition temperature. In contrast, the composites incorporating the overcoated dots sho...