Tuning exciton diffusion, mobility and emission line width in CdSe nanoplatelets via lateral size

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Colloidal quantum wells (CQWs) exhibit unique optoelectronic properties.
• Exciton dynamics in low-dimensional systems are critical for device performance.
• Understanding factors influencing exciton diffusion and mobility is key for advanced applications.

Purpose of the Study:

• To investigate the tunability of exciton diffusion coefficient and mobility in colloidal quantum wells.
• To explore the impact of lateral size and aspect ratio on exciton transport.
• To correlate changes in phonon coupling with exciton mobility.

Main Methods:

• Line width analysis of colloidal quantum wells.
• Theoretical modeling of exciton transport.
• Experimental measurements at cryogenic (4 K) and room temperatures.

Main Results:

• Exciton diffusion coefficient and mobility in CdSe nanoplatelets are tunable via lateral size and aspect ratio.
• Mobility increases significantly with lateral size at 4 K (from ~4x10^3 to >1.4x10^4 cm2 V-1 s-1).
• Exciton diffusion coefficient at 4 K increases from ~1.3 cm2 s-1 to ~5 cm2 s-1 with lateral size.

Conclusions:

• Lateral dimensions of CQWs offer a pathway to tune exciton mobility and diffusion.
• Phonon scattering mechanisms are size-dependent, influencing exciton transport.
• Tunable exciton properties are promising for efficient light harvesting in solar cells and other optoelectronic devices.