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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Efficient Biexciton Interaction in Perovskite Quantum Dots Under Weak and Strong Confinement

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Author(s):
Castaneda, Juan A. ; Nagamine, Gabriel ; Yassitepe, Emre ; Bonato, Luiz G. ; Voznyy, Oleksandr ; Hoogland, Sjoerd ; Nogueira, Ana F. ; Sargent, Edward H. ; Brito Cruz, Carlos H. ; Padilha, Lazaro A.
Total Authors: 10
Document type: Journal article
Source: ACS NANO; v. 10, n. 9, p. 8603-8609, SEP 2016.
Web of Science Citations: 45
Abstract

Cesium lead halide perovskite quantum dots (PQDs) have emerged as a promising new platform for lighting applications. However, to date, light emitting diodes (LED) based on these materials exhibit limited efficiencies. One hypothesized limiting factor is fast nonradiative multiexciton Auger recombination. Using ultrafast spectroscopic techniques, we investigate multicarrier interaction and recombination mechanisms in cesium lead halide PQDs. By mapping the dependence of the biexciton Auger lifetime and the biexciton binding energy on nanomaterial size and composition, we find unusually strong Coulomb interactions among multiexcitons in PQDs. This results in weakly emissive biexcitons and trions, and accounts for low light emission efficiencies. We observe that, for strong confinement, the biexciton lifetime depends linearly on the PQD volume. This dependence becomes sublinear in the weak confinement regime as the PQD size increases beyond the Bohr radius. We demonstrate that Auger recombination is faster in PQDs compared to CdSe nanoparticles having the same volume, suggesting a stronger Coulombic interaction in the PQDs. We confirm this by demonstrating an increased biexciton binding energy, which reaches a maximum of about 100 meV, fully three times larger than in CdSe quantum dots. The biexciton shift can lead to low-threshold optical gain in these materials. These findings also suggest that materials engineering to reduce Coulombic interaction in cesium lead halide PQDs could improve prospects for high efficiency optoelectronic devices. Core-shell structures, in particular type-II nanostructures, which are known to reduce the bandedge Coulomb interaction in CdSe/CdS, could beneficially be applied to PQDs with the goal of increasing their potential in lighting applications. (AU)

FAPESP's process: 14/21928-4 - Hybrid nanostructures in third generation solar cells (3G)
Grantee:Ana Flávia Nogueira
Support type: Regular Research Grants
FAPESP's process: 13/05798-0 - An Investigation of Surface Trap Passivated Colloidal (Ag,Cu)(In,Ga)(Se,S)2 Nanoparticles for Thin Film Solar Cell Applications
Grantee:Emre Yassitepe
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 13/16911-2 - Advanced spectroscopy of novel nanomaterials
Grantee:Lázaro Aurélio Padilha Junior
Support type: Research Grants - Young Investigators Grants
FAPESP's process: 14/18327-9 - Surface trap passivated colloidal quantum dots for application in p-n heterojunction thin film solar cells
Grantee:Emre Yassitepe
Support type: Scholarships abroad - Research Internship - Post-doctor