Density of Trap States and Auger-mediated Electron Trapping in CdTe Quantum-Dot Solids
| Autor: | Boehme, Simon C., Mikel Azpiroz, Jon, Aulin, Yaroslav V., Grozema, Ferdinand C., Vanmaekelbergh, Daniel, Siebbeles, Laurens D. A., Infante, Ivan, Houtepen, Arjan J., Sub Condensed Matter and Interfaces, Condensed Matter and Interfaces |
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| Přispěvatelé: | Sub Condensed Matter and Interfaces, Condensed Matter and Interfaces, Photo Conversion Materials, Theoretical Chemistry, AIMMS |
| Rok vydání: | 2015 |
| Předmět: |
DYNAMICS
defect Photoluminescence SURFACE TRAPS RECOMBINATION Quantum yield Bioengineering Electron Trapping ultrafast spectroscopy symbols.namesake Auger-mediated trapping electrochemistry BLINKING SEMICONDUCTOR NANOCRYSTALS General Materials Science SDG 7 - Affordable and Clean Energy Physics::Atomic Physics Auger-mediated trapping Spectroscopy density functional theory TRANSIENT ABSORPTION-SPECTROSCOPY Condensed Matter::Quantum Gases Chemistry Mechanical Engineering Fermi level quantum dot General Chemistry Condensed Matter Physics CDSE NANOCRYSTALS SIZE electrochemistry Quantum dot LUMINESCENCE symbols Density functional theory Atomic physics ELECTROCHEMICAL CONTROL |
| Zdroj: | Boehme, S C, Azpiroz, J M, Aulin, Y V, Grozema, F C, Vanmaekelbergh, D, Siebbeles, L D A, Infante, I & Houtepen, A J 2015, ' Density of trap states and Auger-mediated electron trapping in CdTe quantum-dot solids ', Nano Letters, pp. 3056-3066 . https://doi.org/10.1021/acs.nanolett.5b00050 Nano Letters, 15(5), 3056. American Chemical Society Nano Letters, 3056-3066. American Chemical Society STARTPAGE=3056;ENDPAGE=3066;ISSN=1530-6984;TITLE=Nano Letters |
| ISSN: | 1530-6992 1530-6984 |
| DOI: | 10.1021/acs.nanolett.5b00050 |
| Popis: | Charge trapping is an ubiquitous process in colloidal quantum-dot solids and a major limitation to the efficiency of quantum dot based devices such as solar cells, LEDs, and thermoelectrics. Although empirical approaches led to a reduction of trapping and thereby efficiency enhancements, the exact chemical nature of the trapping mechanism remains largely unidentified. In this study, we determine the density of trap states in CdTe quantum-dot solids both experimentally, using a combination of electrochemical control of the Fermi level with ultrafast transient absorption and time-resolved photoluminescence spectroscopy, and theoretically, via density functional theory calculations. We find a high density of very efficient electron traps centered similar to 0.42 eV above the valence band. Electrochemical filling of these traps increases the electron lifetime and the photoluminescence quantum yield by more than an order of magnitude. The trapping rate constant for holes is an order of magnitude lower that for electrons. These observations can be explained by Auger-mediated electron trapping. From density functional theory calculations we infer that the traps are formed by dicoordinated Te atoms at the quantum dot surface. The combination of our unique experimental determination of the density of trap states with the theoretical modeling of the quantum dot surface allows us to identify the trapping mechanism and chemical reaction at play during charge trapping in these quantum dots. |
| Databáze: | OpenAIRE |
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