Ideal diode equation for organic heterojunctions. II. the role of polaron pair recombination

N. C. Giebink, B. E. Lassiter, G. P. Wiederrecht, Michael R Wasielewski, S. R. Forrest

Research output: Contribution to journalArticle

188 Citations (Scopus)

Abstract

In paper I, we proposed that current transport in a donor-acceptor heterojunction (HJ) depends on the balance of polaron pair (PP) dissociation and recombination. Here, we directly investigate these processes in archetype planar copper phthalocyanine (CuPc)/C60 and boron subpthalocyanine chloride (SubPc)/C60 HJs. Using intensity-modulated photocurrent spectroscopy (IMPS) along with emission from interfacial Pc/ C60 exciplex states, we monitor the geminate PP density at the HJ as a function of bias and illumination intensity. We find that the SubPc/ C60 PP density is limited by the dynamics of dissociation, where it increases from short circuit, and peaks at open circuit. In contrast, that of CuPc/ C 60 is dominated by faster recombination kinetics and declines monotonically over the same voltage domain. We conclude that the PP recombination rate depends on electric field, and propose a simple expression that qualitatively explains the observed exciplex luminescence and IMPS behavior for these HJs. Our results provide insight into polaron pair recombination, which governs the current-voltage characteristics of organic heterojunctions in the dark and under illumination.

Original languageEnglish
Article number155306
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume82
Issue number15
DOIs
Publication statusPublished - Oct 4 2010

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Gene Conversion
Heterojunctions
heterojunctions
Diodes
diodes
Photocurrents
photocurrents
boron chlorides
Lighting
illumination
Spectroscopy
dissociation
short circuits
electric potential
Current voltage characteristics
Chlorides
Short circuit currents
spectroscopy
Boron
Luminescence

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Ideal diode equation for organic heterojunctions. II. the role of polaron pair recombination. / Giebink, N. C.; Lassiter, B. E.; Wiederrecht, G. P.; Wasielewski, Michael R; Forrest, S. R.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 82, No. 15, 155306, 04.10.2010.

Research output: Contribution to journalArticle

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