AI Article Synopsis
- Researchers synthesized 3.5 monolayer core/crown CdSe/CdS nanoplatelets (NPLs) with varying crown sizes, achieving strong blue emission and a photoluminescence quantum efficiency of up to 55%.
- The study found that these core/crown NPLs showed improved PL intensity decay compared to core-only NPLs, indicating reduced charge trapping and better emission properties.
- Biexciton-mediated optical gain was observed in both types of NPLs, with greater material gain coefficients and lower thresholds in crowned NPLs, while the gain lifetimes were limited by rapid trapping and high exciton densities.
Article Abstract
The application of CdSe nanoplatelets (NPLs) in the ultraviolet/blue region remains an open challenge due to charge trapping typically leading to limited photoluminescence quantum efficiency (PL QE) and sub-bandgap emission in core-only NPLs. Here, we synthesized 3.5 monolayer core/crown CdSe/CdS NPLs with various crown dimensions, exhibiting saturated blue emission and PL QE up to 55%. Compared to core-only NPLs, the PL intensity decays monoexponentially over two decades due to suppressed deep trapping and delayed emission. In both core-only and core/crown NPLs we observe biexciton-mediated optical gain between 470 and 510 nm, with material gain coefficients up to 7900 cm and consistently lower gain thresholds in crowned NPLs. Gain lifetimes are limited to 40 ps, due to residual ultrafast trapping and higher exciton densities at threshold. Our results provide guidelines for rational optimization of thin CdSe NPLs toward lighting and light-amplification applications.
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| http://dx.doi.org/10.1021/acs.nanolett.2c05061 | DOI Listing |
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