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The Role of Excitons and Free Charges in the Excited-State Dynamics of Solution-Processed Few-Layer MoS2 Nanoflakes
- Source :
- The Journal of Physical Chemistry C
- Publication Year :
- 2016
- Publisher :
- American Chemical Society (ACS), 2016.
-
Abstract
- Solution processed semiconducting transition metal dichalcogenides are emerging as promising two dimensional materials for photovoltaic and optoelectronic applications. Here we have used transient absorption spectroscopy to provide unambiguous evidence and distinct signatures of photogenerated excitons and charges in solution processed few layer MoS2 nanoflakes (10-20 layers). We find that photoexcitation above the direct energy gap results in the ultrafast generation of a mixture of free charges in direct band states and of excitons. While the excitons are rapidly trapped the free charges are long lived with nanosecond recombination times. The different signatures observed for these species enable the experimental extraction of the exciton binding energy which we find to be ~80 meV in the nanoflakes in agreement with reported values in the bulk material. Carrier density dependent measurements bring new insights about the many body interactions between free charges resulting in band gap renormalization effects in the few layer MoS2 nanoflakes.
- Subjects :
- Band gap
Chemistry
Exciton
02 engineering and technology
Nanosecond
021001 nanoscience & nanotechnology
01 natural sciences
7. Clean energy
Molecular physics
Surfaces, Coatings and Films
Electronic, Optical and Magnetic Materials
Photoexcitation
Condensed Matter::Materials Science
General Energy
Excited state
0103 physical sciences
Ultrafast laser spectroscopy
Physical and Theoretical Chemistry
Atomic physics
010306 general physics
0210 nano-technology
Spectroscopy
Biexciton
Subjects
Details
- ISSN :
- 19327455 and 19327447
- Volume :
- 120
- Database :
- OpenAIRE
- Journal :
- The Journal of Physical Chemistry C
- Accession number :
- edsair.doi.dedup.....8f6fd9b0e5199393ffcc4fa83acd4286