Evidence for high-efficiency exciton dissociation at polymer/single-walled carbon nanotube interfaces in planar nano-heterojunction photovoltaics

Moon Ho Ham, Geraldine L C Paulus, Chang Young Lee, Changsik Song, Kourosh Kalantar-Zadeh, Wonjoon Choi, Jae Hee Han, Michael S. Strano

Research output: Contribution to journalArticle

85 Citations (Scopus)

Abstract

There is significant interest in combining carbon nanotubes with semiconducting polymers for photovoltaic applications because of potential advantages from smaller exciton transport lengths and enhanced charge separation. However, to date, bulk heterojunction (BHJ) devices have demonstrated relatively poor efficiencies, and little is understood about the polymer/nanotube junction. To investigate this interface, we fabricate a planar nano-heterojunction comprising well-isolated millimeter-long single-walled carbon nanotubes underneath a poly(3-hexylthiophene) (P3HT) layer. The resulting junctions display photovoltaic efficiencies per nanotube ranging from 3% to 3.82%, which exceed those of polymer/nanotube BHJs by a factor of 50-100. The increase is attributed to the absence of aggregate formation in this planar device geometry. It is shown that the polymer/nanotube interface itself is responsible for exciton dissociation. Typical open-circuit voltages are near 0.5 V with fill factors of 0.25-0.3, which are largely invariant with the number of nanotubes per device and P3HT thickness. A maximum efficiency is obtained for a 60 nm-thick P3HT layer, which is predicted by a Monte Carlo simulation that takes into account exciton generation, transport, recombination, and dissociation. This platform is promising for further understanding the potential role of polymer/nanotube interfaces for photovoltaic applications.

Original languageEnglish
Pages (from-to)6251-6259
Number of pages9
JournalACS Nano
Volume4
Issue number10
DOIs
Publication statusPublished - 2010 Oct 26
Externally publishedYes

Fingerprint

Single-walled carbon nanotubes (SWCN)
Excitons
Nanotubes
Heterojunctions
heterojunctions
nanotubes
Polymers
carbon nanotubes
excitons
dissociation
polymers
Semiconducting polymers
heterojunction devices
Carbon Nanotubes
Open circuit voltage
polarization (charge separation)
open circuit voltage
LDS 751
Carbon nanotubes
platforms

Keywords

  • exciton diffusion
  • Monte Carlo modeling
  • n-doping of carbon nanotubes
  • organic photovoltaics
  • polymer hybrid solar cells
  • single-walled carbon nanotubes
  • well-aligned carbon nanotubes

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Physics and Astronomy(all)

Cite this

Evidence for high-efficiency exciton dissociation at polymer/single-walled carbon nanotube interfaces in planar nano-heterojunction photovoltaics. / Ham, Moon Ho; Paulus, Geraldine L C; Lee, Chang Young; Song, Changsik; Kalantar-Zadeh, Kourosh; Choi, Wonjoon; Han, Jae Hee; Strano, Michael S.

In: ACS Nano, Vol. 4, No. 10, 26.10.2010, p. 6251-6259.

Research output: Contribution to journalArticle

Ham, Moon Ho ; Paulus, Geraldine L C ; Lee, Chang Young ; Song, Changsik ; Kalantar-Zadeh, Kourosh ; Choi, Wonjoon ; Han, Jae Hee ; Strano, Michael S. / Evidence for high-efficiency exciton dissociation at polymer/single-walled carbon nanotube interfaces in planar nano-heterojunction photovoltaics. In: ACS Nano. 2010 ; Vol. 4, No. 10. pp. 6251-6259.
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