Planar and textured heterojunction organic photovoltaics based on chloroindium phthalocyanine (ClInPc) versus titanyl phthalocyanine (TiOPc) donor layers

Weining Wang, Diogenes Placencia, Neal R. Armstrong

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

Planar and textured heterojunction solar cells (OPVs) are reported for vacuum deposited chloroindium phthalocyanine (ClInPc)/C60 heterojunctions, and their response compared to previously explored OPVs based on titanyl phthalocyanine (TiOPc)/C60 heterojunctions. As for TiOPc/C60 OPVs, the photoelectrical activity of ClInPc/C60 OPVs extends well into the near infrared, with good activity out to ca. 900 nm. As-deposited ClInPc films (Phase I) produce open-circuit photopotentials, VOC as high as ca. 0.8 V (Phase I form of ClInPc), ca. 0.15 V larger than previously observed for Phase I TiOPc/C60 OPVs. The offsets in frontier orbital energies (EHOMOPc-ELUMOC60) revealed by UV-photoemission studies (UPS) are slightly smaller for ClInPc/C60 versus TiOPc/C 60 heterojunctions, and the interface dipole contribution (shift in local vacuum level) to these offsets is in the opposite direction for ClInPc/C60 versus TiOPc/C60 heterojunctions, or missing altogether, suggesting differences in molecular interaction at the Pc/C 60 interface. Higher VOC values are correlated with lower reverse saturation currents, Jo, for ClInPc/C60, versus other Pc or pentacene/C60 heterojunctions, suggesting weak intermolecular interactions at the ClInPc/C60 interface and large barriers to dark charge injection. Solvent annealing of the ClInPc films enhances the near-IR response, and textures the Pc film, enhancing the Pc/C 60 interfacial contact area and the short-circuit photocurrent, JSC. JSC under AM 1.5 illumination conditions was estimated by integration of the incident photon current efficiency (IPCE) response, to compare relative power conversion efficiencies for the two different device types. The estimated efficiency of Phase I ClInPc/C 60 OPVs is ca. 2.6%. The estimated AM 1.5 efficiency of ClInPc/C 60 OPVs with solvent annealed Pc layers is estimated to be ca. 3.3%, arising from the extensive texturing achieved of the Pc layer, which nearly doubles JSC for the Phase II versus Phase I Pc films.

Original languageEnglish (US)
Pages (from-to)383-393
Number of pages11
JournalOrganic Electronics
Volume12
Issue number2
DOIs
StatePublished - Feb 2011

Keywords

  • Heterojunction
  • Interface dipole
  • Near-IR
  • Organic solar cell
  • Phthalocyanine
  • UV-photoemission

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering

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