Suppressed Blinking and Auger Recombination in Near-Infrared Type-II InP/CdS Nanocrystal Quantum Dots

• Published in: Nano letters Vol. 12; no. 11; pp. 5545 - 5551
• Main Authors: Dennis, Allison M, Mangum, Benjamin D, Piryatinski, Andrei, Park, Young-Shin, Hannah, Daniel C, Casson, Joanna L, Williams, Darrick J, Schaller, Richard D, Htoon, Han, Hollingsworth, Jennifer A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14.11.2012
• Subjects: Applied sciences; Augers; Blinking; Cadmium Compounds - chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Control systems; Cross-disciplinary physics: materials science; rheology; Electronic structure; Electronics; Electrons; Exact sciences and technology; Indium - chemistry; Indium phosphides; Materials science; Mathematical analysis; Microscopy, Electron, Transmission - methods; Molecular electronics, nanoelectronics; Nanocrystalline materials; Nanocrystals; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Nanotechnology - methods; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Palladium - chemistry; Particle Size; Phosphates - chemistry; Photochemistry - methods; Physics; Quantum Dots; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Spectrometry, Fluorescence - methods; Spectroscopy, Near-Infrared - methods; Sulfides - chemistry; Temperature; Time Factors; core/shell heterostructure; Fluorescence blinking suppression; near-infrared; biexciton lifetime; Auger recombination; type-II nanocrystal quantum dot; Quantum dots; Non radiative recombination; Core shell structure; Photoluminescence; Theoretical study; Radiative lifetimes; Cadmium sulfide; III-V compound; Indium phosphide; Biexcitons; Near infrared radiation; Lifetime; Electronic structure; Monolayers; Size effect; Photoelectronic properties; Nanostructured materials; Heterostructures; Nanocrystal; Photobleaching; III-V semiconductors
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl302453x

Nonblinking excitonic emission from near-infrared and type-II nanocrystal quantum dots (NQDs) is reported for the first time. To realize this unusual degree of stability at the single-dot level, novel InP/CdS core/shell NQDs were synthesized for a range of shell thicknesses (∼1–11 monolayers of CdS). Ensemble spectroscopy measurements (photoluminescence peak position and radiative lifetimes) and electronic structure calculations established the transition from type-I to type-II band alignment in these heterostructured NQDs. More significantly, single-NQD studies revealed clear evidence for blinking suppression that was not strongly shell-thickness dependent, while photobleaching and biexciton lifetimes trended explicitly with extent of shelling. Specifically, very long biexciton lifetimesup to >7 nswere obtained for the thickest-shell structures, indicating dramatic suppression of nonradiative Auger recombination. This new system demonstrates that electronic structure and shell thickness can be employed together to effect control over key single-dot and ensemble NQD photophysical properties.