Ultrafast exciton many-body interactions and hot-phonon bottleneck in colloidal cesium lead halide perovskite nanocrystals

Defect-tolerant perovskite nanocrystals of the general formula Cs-Pb-X3 (where X=Cl, Br, and I) have shown exceptional potential in fundamental physics as well as in novel optoelectronic applications as the next generation of solar cells. Although exciton many-body interactions such as biexciton Sta...

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Bibliographic Details
Published in:Physical review. B 2018-09, Vol.98 (11), p.115418, Article 115418
Main Authors: Mondal, Anirban, Aneesh, J., Kumar Ravi, Vikash, Sharma, Rituraj, Mir, Wasim J., Beard, Mathew C., Nag, Angshuman, Adarsh, K. V.
Format: Article
Language:English
Subjects:
Augers
Carrier density
Cesium
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Correlation analysis
Dependence
Energy gap
Excitons
Many body problem
Nanocrystals
Optoelectronics
Perovskites
Photovoltaic cells
Solar cells
SOLAR ENERGY
Thermalization (energy absorption)
ultrafast phenomena
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Summary:Defect-tolerant perovskite nanocrystals of the general formula Cs-Pb-X3 (where X=Cl, Br, and I) have shown exceptional potential in fundamental physics as well as in novel optoelectronic applications as the next generation of solar cells. Although exciton many-body interactions such as biexciton Stark shift, state filling, and Auger recombination are studied extensively, other important correlated effects, such as band gap renormalization (BGR) and hot-phonon bottleneck, are not explored in these nanocrystals. Here we experimentally demonstrate the carrier density dependence of the BGR and an effective hot-phonon bottleneck in CsPb(Cl0.20Br0.80)3 mixed-halide nanocrystals. The results are compared with two other halide compositions, namely, CsPbBr3 and CsPb(Br0.55I0.45)3 nanocrystals with varying band gaps. The optical response of the nanocrystals changes dramatically across the spectral range of many hundreds of meV at high carrier density due to large BGR. We have calculated the BGR constant ≈(6.0±0.3)×10−8eV cm for CsPb(Cl0.20Br0.80)3 nanocrystals that provides the amount of band gap shift as a function of carrier density. In these nanocrystals, an efficient hot-phonon bottleneck is observed at a carrier density of 3.1×1017cm−3 that slows down the thermalization by 1 order of magnitude. Our findings reveal that the complex kinetic profile of the exciton dynamics can be analyzed by the global target analysis using the sequential model with increasing lifetimes.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.98.115418