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Abnormal scaling of excitons in phosphorene quantum dots
摘要： Excitonic states of a many-electron system in phosphorene quantum dots (PQDs) are investigated theoretically by using a configuration interaction approach. For a triangular PQD in various dielectric environments, its exciton is found to obey two distinct scaling rules. When there is strong screening effect present in the nanodot, the exciton binding energy (?ex) is shown to be around ?150 meV as the long-range Coulomb interactions are totally suppressed and increases to about 100 meV when the effective dielectric constant (εr) decreases to 12.5. Over this range of εr, ?ex is found to be well fitted into a quadratic form of ε?1 r like the case of bulk three-dimensional semiconductors nor linearly with ε?1 r like the case previously reported for graphene nanostructures. When εr is reduced below 10.0, however, ?ex is shown to exhibit a perfect linear relation with ε?1 r, which behaves just like that of a two-dimensional graphene sheet. On the other hand, with the reduced εr, the quasiparticle gap is found to decrease instead of increase like in most of semiconductor nanostructures. As a result, it is revealed that the relationship of ?ex with the quasi-particle gap deviates largely from the linear one previously reported for graphene and many other two-dimensional materials.
关键词： excitonic states,dielectric environments,phosphorene quantum dots,scaling rules,configuration interaction approach
更新于2025-09-23 15:19:57
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Electrochemical transformation of black phosphorous to phosphorene quantum dots: effect of nitrogen doping
摘要： We present a comparative analysis of the structural and optical properties of electrosynthesized PQDs, a new class of size-tunable luminescent materials and their nitrogen doped counter parts(NPQDs). Nitrogen doping onto phopshorene lattice could be realized in situ at room temperature using either nitrogen containing electrolyte and/or supporting electrolyte in the solution. An increased quantum ef?ciency as well as redox behavior has been observed for PQDs upon nitrogen doping and a critical analysis of the effect of nitrogen on the structural, optical and electrochemical properties of PQDs suggests several potential bene?ts of applications ranging from electrocatalysts and molecular electronics to different types of sensors and bioimaging.
关键词： Nitrogen Doping,Phosphorene Quantum Dots,Black Phosphorus,Electrosynthesis
更新于2025-09-16 10:30:52
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Photoluminescence mechanism of phosphorene quantum dots (PQDs) produced by pulsed laser ablation in liquids
摘要： Phosphorene quantum dots (PQDs) with high photoluminescence (PL) quantum yield were fabricated through pulsed laser ablation of black phosphorus in liquids. The PL emission showed excitation wavelength-independent features due to the suf?cient passivation by oxygen-containing substituents derived from the ablation-decomposed solvent molecules. There were four peaks in the PL pro?le showing a multi-frequency PL effect, which provided a viable route to investigate the PL mechanism via the detailed structures of the PL pro?le. The two peaks at shorter wavelengths were attributed to the intrinsic PL transitions. The two peaks at longer wavelengths were assigned to the transitions from the lowest unoccupied molecular orbital to the two-surface states. The positions of the four peaks are redshifted with increasing solvent molecular chain length due to the passivation effect. The intense, excitation wavelength-independent, multifrequency and blue-violet PL emissions indicate the potential application in semiconductor light sources.
关键词： semiconductor light sources,pulsed laser ablation,photoluminescence,phosphorene quantum dots
更新于2025-09-12 10:27:22