Mapping the Exciton Diffusion in Semiconductor Nanocrystal Solids

作者：Kholmicheva Natalia; Moroz Pavel; Bastola Ebin; Razgoniaeva Natalia; Bocanegra Jesus; Shaughnessy Martin; Porach Zack; Khon Dmitriy; Zamkov Mikhail^*

来源：ACS Nano, 2015, 9(3): 2926-2937.

DOI：10.1021/nn507322y

• charge transport
• thin films
• plasmonics
• colloidal quantum dots

Colloidal nanocrystal solids represent an emerging class of functional Materials thathOld strong promise for device applications. The macroscopic properties of these disordered assemblies are determined by complex trajectories of extiton diffusion processes, which are still poorly Understood. Owing to the lack of theoretical insight, experimental strategies for probing the exciton dynamics in quantum dot solids are in great demand. Here, we develop an experimental technique for mapping the motion of excitons in semiconductor nanocrystal films with a subdiffraction spatial sensitivity and a picosecond temporal resolution: This was accomplished by doping PbS nanocrystal solids with metal nanciparticleS that force the exciton dissociation attnown distances from their birth. The optical signature of the exciton motion was then inferred from the changesin the emission lifetime, which was mapped to the location.of excitori quenching sites. By correlating the metal metal interparticle diStancein the film with corresponding changes in the emission lifetime, we could obtain important transport characteristics, including the exciton diffusion length, the number of predissociation hops, the rate of interparticle energy transfer, and the exciton diffusivity. The benefits of this approach to device applications were demonstrated through the use of two representative film morphelogies featuring weak and strong interparticle coupling.

• 出版日期2015-3