Method for characterizing bulk recombination using photoinduced absorption

Nora Wilson, Simon Sandén, Oskar Sandberg, Ronald Österbacka

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Abstract

The influence of reaction order and trap-assisted recombination on continuous-wave photoinduced absorption measurements is clarified through analytical calculations and numerical simulations. The results reveal the characteristic influence of different trap distributions and enable distinguishing between shallow exponential and Gaussian distributions and systems dominated by direct recombination by analyzing the temperature dependence of the in-phase and quadrature signals. The identifying features are the intensity dependence of the in-phase at high intensity, PAI∝IγHI, and the frequency dependence of the quadrature at low frequency, PAQ∝ωγLF. For direct recombination, γHI and γLF are temperature independent, and for an exponential distribution, they depend on the characteristic energy Ech as γHI=1/(1+Ech/kT) and γLF=kT/Ech, while a Gaussian distribution shows γHI and γLF as functions of I and ω, respectively.

Original languageUndefined/Unknown
Pages (from-to)
JournalJournal of Applied Physics
Volume121
Issue number9
DOIs
Publication statusPublished - 2017
MoE publication typeA1 Journal article-refereed

Keywords

  • photoinduced absorption
  • Organic semiconductors
  • Charge recombination
  • recombination
  • trap-assisted recombination
  • disordered semiconductors
  • optical measurements

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