Confined Excitons in Spherical-Like Halide Perovskite Quantum Dots

Barfuber, Anja; Rieger, Sebastian; Dey, Amrita; Tosun, Ahmet; Akkerman, Quinten A.; Debnath, Tushar und Feldmann, Jochen (2022): Confined Excitons in Spherical-Like Halide Perovskite Quantum Dots. In: Nano Letters, Bd. 22, Nr. 22: S. 8810-8817

Abstract

Quantum dots (QDs) offer unique physical proper-ties and novel application possibilities like single-photon emitters for quantum technologies. While strongly confined III-V and II- VI QDs have been studied extensively, their complex valence band structure often limits clear observations of individual transitions. In recently emerged lead-halide perovskites, band degeneracies are absent around the bandgap reducing the complexity of optical spectra. We show that for spherical-like CsPbBr3 QDs with diameters > 6 nm, excitons confine with respect to their center-of-mass motion leading to well-pronounced resonances in their absorption spectra. Optical pumping of the lowest-confined exciton with femtosecond laser pulses not only bleaches all excitons but also reveals a series of distinct induced absorption resonances which we attribute to exciton-to-biexciton transitions and are red-shifted by the biexciton binding energy (& SIM;40 meV). The temporal dynamics of the bleached excitons further support our exciton confinement model. Our study provides the first insight into confined excitons in CsPbBr3 QDs and gives a detailed understanding of their linear and nonlinear optical spectra.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 1530-6984
• Sprache: Englisch