Multiple exciton generation induced enhancement of the photoresponse of pulsed-laser-ablation synthesized single-wall-carbon-nanotube/PbS-quantum-dots nanohybrids

Ibrahima Ka, Vincent Le Borgne, Kazunori Fujisawa, Takuya Hayashi, Yoong Ahm Kim, Morinobu Endo, Dongling Ma, My Ali El Khakani

Research output: Contribution to journalArticle

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Abstract

The pulsed laser deposition method was used to decorate appropriately single wall carbon nanotubes (SWCNTs) with PbS quantum dots (QDs), leading to the formation of a novel class of SWCNTs/PbS-QDs nanohybrids (NHs), without resorting to any ligand engineering and/or surface functionalization. The number of laser ablation pulses (NLp) was used to control the average size of the PbS-QDs and their coverage on the SWCNTs' surface. Photoconductive (PC) devices fabricated from these SWCNTs/PbS-QDs NHs have shown a significantly enhanced photoresponse, which is found to be PbS-QD size dependent. Wavelength-resolved photocurrent measurements revealed a strong photoconductivity of the NHs in the UV-visible region, which is shown to be due to multiple exciton generation (MEG) in the PbS-QDs. For the 6.5 nm-diameter PbS-QDs (with a bandgap (Eg) = 0.86 eV), the MEG contribution of the NHs based PC devices was shown to lead to a normalized internal quantum efficiency in excess of 300% for photon energies ≥4.5Eg. While the lowest MEG threshold in our NHs based PC devices is found to be of ∼2.5Eg, the MEG efficiency reaches values as high as 0.9 ± 0.1.

Original languageEnglish (US)
Article number20083
JournalScientific reports
Volume6
DOIs
StatePublished - Feb 2 2016

All Science Journal Classification (ASJC) codes

  • General

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