Issue 2, 2018

All-inorganic perovskite nanocrystal assisted extraction of hot electrons and biexcitons from photoexcited CdTe quantum dots

Abstract

Excitation of semiconductor quantum dots (QDs) by photons possessing energy higher than the band-gap creates a hot electron–hole pair, which releases its excess energy as waste heat or under certain conditions (when > 2Eg) produces multiple excitons. Extraction of these hot carriers and multiple excitons is one of the key strategies for enhancing the efficiency of QD-based photovoltaic devices. However, this is a difficult task as competing carrier cooling and relaxation of multiple excitons (through Auger recombination) are ultrafast processes. Herein, we study the potential of all-inorganic perovskite nanocrystals (NCs) of CsPbX3 (X = Cl, Br) as harvesters of these short-lived species from photo-excited CdTe QDs. The femtosecond transient absorption measurements show CsPbX3 mediated extraction of both hot and thermalized electrons of the QDs (under a low pump power) and (under a high pump fluence) extraction of multiple excitons prior to their Auger assisted recombination. A faster timescale of thermalized electron transfer (∼2 ps) and a higher extraction efficiency of hot electrons (∼60%) are observed in the presence of CsPbBr3. These observations demonstrate the potential of all-inorganic perovskite NCs in the extraction of these short-lived energy rich species implying that complexes of the QDs and perovskite NCs are better suited for improving the efficiency of QD-sensitized solar cells.

Graphical abstract: All-inorganic perovskite nanocrystal assisted extraction of hot electrons and biexcitons from photoexcited CdTe quantum dots

Supplementary files

Article information

Article type
Paper
Submitted
20 oct. 2017
Accepted
27 nov. 2017
First published
28 nov. 2017

Nanoscale, 2018,10, 639-645

All-inorganic perovskite nanocrystal assisted extraction of hot electrons and biexcitons from photoexcited CdTe quantum dots

N. Mondal, A. De and A. Samanta, Nanoscale, 2018, 10, 639 DOI: 10.1039/C7NR07830G

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