Enhancing exciton diffusion in organic photovoltaics cells incorporating dilute donor layers

S. Matthew Menke, Russell J. Holmes

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In this work we measure the exciton diffusion length (LD) of the electron donor material boron subphthalocyanine chloride (SubPc) as a function of concentration in a wide energy gap host material, effectively modulating the intermolecular separation. It is shown that the LD of neat SubPc (LD = 10.7 nm) can be increased by ∼50% at a concentration of 25 wt.% (LD = 15.4 nm). The enhancement in LD is attributed to the optimization of the parameters that control Förster energy transfer. Furthermore, we show that enhanced LD can be translated to dilute donor OPVs that demonstrate an enhanced power efficiency of ηP = 4.4%, a ∼30% increase relative to OPV devices based on neat SubPc and rivaling the efficiency of corresponding bulk heterojunction devices based on SubPc and C60. Kinetic Monte Carlo modeling of exciton dynamics in these devices suggests that optimal incorporation of dilute donor layers with enhanced LD depends intimately on the interface. Specifically, an imbalance in energy transfer across the dilute donor interface imparts inhomogeneity in the energy transfer landscape, dramatically affecting exciton motion. Overall, this work highlights the opportunity for designing future organic semiconductors that have longer LD as well as OPV architectures that are directly optimized for enhanced exciton diffusion.

Original languageEnglish (US)
Title of host publication2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages51-56
Number of pages6
ISBN (Electronic)9781479943982
DOIs
StatePublished - Oct 15 2014
Event40th IEEE Photovoltaic Specialist Conference, PVSC 2014 - Denver, United States
Duration: Jun 8 2014Jun 13 2014

Publication series

Name2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014

Other

Other40th IEEE Photovoltaic Specialist Conference, PVSC 2014
CountryUnited States
CityDenver
Period6/8/146/13/14

Keywords

  • energy transfer
  • exciton diffusion
  • organic semiconductor
  • photovoltaics

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