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- 摘要
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Photoluminescence Decay of Colloidal Quantum Dots: Reversible Trapping and the Nature of the Relevant Trap States
摘要： Interfaces are crucial factors in shaping the properties of colloidal quantum dots (QDs), in particular the size-dependent optical properties that are a hallmark of these materials. However, the role played by the interfaces associated with QDs on the kinetics of photoluminescence (PL) decay of these nanocrystals is not fully understood even for the most extensively investigated II-VI QDs. In particular, interfaces are a hotbed of trapping sites over which control is essential for efficient performance of QD-based devices, because traps condition PL lifetimes and may be related to PL intermittency. In this work, we analyze the room-temperature PL decay of drop-cast films of CdSe/ZnS QDs varying a number of factors (casting solvent, capping ligands, core/shell interface character). We show how the use of a function that accounts for reversible trapping of photogenerated charge carriers with physically meaningful parameters (time constant, trapping and detrapping rate constants, and average number of traps per QD) can provide valuable information concerning the relevant interfaces, and therefore the nature of the trap states, involved in the recombination of those charge carriers. This approach should be applicable to QDs of a variety of compositions as well as materials beyond inorganic semiconductors.
关键词： photoluminescence decay,trap states,reversible trapping,CdSe/ZnS QDs,colloidal quantum dots
更新于2025-09-11 14:15:04
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Photodetecting Heterostructures from Graphene and Encapsulated Colloidal Quantum Dot Films
摘要： Heterostructure devices consisting of graphene and colloidal quantum dots (QDs) have been remarkably successful as photodetectors and have opened the door to technological applications based on the combination of these low-dimensional materials. This work explores the photodetection properties of a heterostructure consisting of a graphene field effect transistor covered by a film of silica-encapsulated colloidal QDs. Defects at the surface of the silica shell trap optically excited charge carriers, which simultaneously enables photodetection via two mechanisms: photogating, resulting in a net p-doping of the device, and Coulombic scattering of charge carriers in the graphene, producing an overall decrease in the current magnitude.
关键词： heterostructures,photogating,graphene,Coulombic scattering,colloidal quantum dots,photodetectors
更新于2025-09-11 14:15:04
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Applied Nanophotonics || Lighting with nanostructures
摘要： This chapter considers application of various nanostructures in lighting devices and components. It includes an introduction to photometry and color perception by humans, and discussion of colloidal quantum dots as spectral converters in display devices and lighting sources; advances in development of colloidal quantum dot light-emitting diodes (LEDs); epitaxial quantum well structures as the core technology in solid-state lighting; the potential for metal nanostructures to improve efficiency of light sources; and the outlook for challenging issues in this field. The new trends in eye-friendly customized lighting and the lighting adapted to human biorhythms are covered, and possible application of residential lighting systems for wireless optical communication (Li-Fi) are discussed.
关键词： colloidal quantum dots,metal nanostructures,nanostructures,LEDs,Li-Fi,solid-state lighting,lighting devices
更新于2025-09-09 09:28:46