Ultrafast charge-and energy-transfer dynamics in conjugated polymer: Cadmium selenide nanocrystal blends

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Frederik S.F. Morgenstern - , University of Cambridge (Author)
  • Akshay Rao - , University of Cambridge (Author)
  • Marcus L. Böhm - , University of Cambridge (Author)
  • René J.P. Kist - , University of Cambridge (Author)
  • Yana Vaynzof - , University of Cambridge (Author)
  • Neil C. Greenham - , University of Cambridge (Author)

Abstract

Hybrid nanocrystal-polymer systems are promising candidates for photovoltaic applications, but the processes controlling charge generation are poorly understood. Here, we disentangle the energy-and charge-transfer processes occurring in a model system based on blends of cadmium selenide nanocrystals (CdSe-NC) with poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4- phenylene vinylene] (MDMO-PPV) using a combination of time-resolved absorption and luminescence measurements. The use of different capping ligands (n-butylamine, oleic acid) as well as thermal annealing allows tuning of the polymer-nanocrystal interaction. We demonstrate that energy transfer from MDMO-PPV to CdSe-NCs is the dominant exciton quenching mechanism in nonannealed blends and occurs on ultrafast time scales (<1 ps). Upon thermal annealing electron transfer becomes competitive with energy transfer, with a transfer rate of 800 fs independent of the choice of the ligand. Interestingly, we find hole transfer to be much less efficient than electron transfer and to extend over several nanoseconds. Our results emphasize the importance of tuning the organic-nanocrystal interaction to achieve efficient charge separation and highlight the unfavorable hole-transfer dynamics in these blends.

Details

Original languageEnglish
Pages (from-to)1647-1654
Number of pages8
JournalACS nano
Volume8
Issue number2
Publication statusPublished - 25 Feb 2014
Peer-reviewedYes
Externally publishedYes

Keywords

Sustainable Development Goals

Keywords

  • CdSe, charge transfer, hybrid, nanocrystals, photoluminescence, photovoltaics, polymer, transient absorption