Semiconductor colloidal quantum wells(CQWs)with atomic-precision layer thickness are rapidly gaining attention for next-generation optoelectronic applications due to their tunable optical and electronic properties.In ...Semiconductor colloidal quantum wells(CQWs)with atomic-precision layer thickness are rapidly gaining attention for next-generation optoelectronic applications due to their tunable optical and electronic properties.In this study,we investigate the dielectric and optical characteristics of CdSe CQWs with monolayer numbers ranging from 2 to 7,synthesized via thermal injection and atomic layer(c-ALD)deposition techniques.Through a combination of spectroscopic ellipsometry(SE)and first-principles calculations,we demonstrate the significant tunability of the bandgap,refractive index,and extinction coefficient,driven by quantum confinement effects.Our results show a decrease in bandgap from 3.1 to 2.0 eV as the layer thickness increases.Furthermore,by employing a detailed analysis of the absorption spectra,accounting for exciton localization and asymmetric broadening,we precisely capture the relationship between monolayer number and exciton binding energy.These findings offer crucial insights for optimizing CdSe CQWs in optoelectronic device design by leveraging their layer-dependent properties.展开更多
CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significa...CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significantly enhances the photophysical property of CdSe NPLs.Laser spectroscopy techniques reveal suppressed electronic and hole trapping at lateral surfaces,leading to a 4.2-fold increase in photoluminescence quantum yield and a shortened emission lifetime from13.5 to 4.8 ns.In addition,amplified spontaneous emission is achieved under nanosecond pulse pumping,with thresholds of0.75 to 0.16 mJ/cm^(2)for CdSe and CdSe/CdSeS NPLs,respectively.By integrating CdSe/CdSeS NPLs with high-refractiveindex SiO2scatters,coherent random lasing is realized at a threshold of 0.21 mJ/cm^(2).These findings highlight the critical role of lateral surface passivation in optimizing optical gain and pave the way for low-cost,multifunctional nanophotonic devices.展开更多
基金supported by the National Natural Science Foundation of China(62205180)the Natural Science Foundation of Shandong Province(ZR2022QF029)the Taishan Scholar Program of Shandong Province(Young Scientist).
文摘Semiconductor colloidal quantum wells(CQWs)with atomic-precision layer thickness are rapidly gaining attention for next-generation optoelectronic applications due to their tunable optical and electronic properties.In this study,we investigate the dielectric and optical characteristics of CdSe CQWs with monolayer numbers ranging from 2 to 7,synthesized via thermal injection and atomic layer(c-ALD)deposition techniques.Through a combination of spectroscopic ellipsometry(SE)and first-principles calculations,we demonstrate the significant tunability of the bandgap,refractive index,and extinction coefficient,driven by quantum confinement effects.Our results show a decrease in bandgap from 3.1 to 2.0 eV as the layer thickness increases.Furthermore,by employing a detailed analysis of the absorption spectra,accounting for exciton localization and asymmetric broadening,we precisely capture the relationship between monolayer number and exciton binding energy.These findings offer crucial insights for optimizing CdSe CQWs in optoelectronic device design by leveraging their layer-dependent properties.
基金supported by the National Natural Science Foundation of China(Grant No.62174079)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2404006)Science,Technology and Innovation Commission of Shenzhen Municipality(Grant No.JCYJ20220530113015035)。
文摘CdSe nanoplatelets(NPLs)are promising candidates for on-chip light sources,yet their performance is hindered by surface defects and inefficient optical gain.Herein,we demonstrate that CdSeS crown passivation significantly enhances the photophysical property of CdSe NPLs.Laser spectroscopy techniques reveal suppressed electronic and hole trapping at lateral surfaces,leading to a 4.2-fold increase in photoluminescence quantum yield and a shortened emission lifetime from13.5 to 4.8 ns.In addition,amplified spontaneous emission is achieved under nanosecond pulse pumping,with thresholds of0.75 to 0.16 mJ/cm^(2)for CdSe and CdSe/CdSeS NPLs,respectively.By integrating CdSe/CdSeS NPLs with high-refractiveindex SiO2scatters,coherent random lasing is realized at a threshold of 0.21 mJ/cm^(2).These findings highlight the critical role of lateral surface passivation in optimizing optical gain and pave the way for low-cost,multifunctional nanophotonic devices.
