Origin of photogenerated carrier recombination at the metal-active layer interface in polymer solar cells

Mukesh Kumar, Ashish Dubey, Khan Mamun Reza, Nirmal Adhikari, Qiquan Qiao, Venkat Bommisetty

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

The role of the metal-active layer interface in photogenerated recombination has been investigated using nanoscale current sensing atomic force microscopy (CS-AFM) and intensity modulated photocurrent spectroscopy (IMPS) in as-deposited, pre-annealed and post-annealed bulk heterojunction (BHJ) solar cells. Aluminum (Al) confined post-annealed BHJ solar cells exhibited a significantly improved device efficiency compared to pre-annealed BHJ solar cells having similar photocarrier harvesting ability in the active layer. The nanoscale topography and CS-AFM results indicate a uniform PCBM rich phase at the metal-active layer interface in the post-annealed cells, but PCBM segregation in the pre-annealed cells. These two different annealing processes showed different carrier dynamics revealed using IMPS under various light intensities. The IMPS results suggest reduced photo generated carrier recombination in uniform PCBM rich post-annealed BHJ solar cells. This study reveals the importance of the metal-bend interface in BHJ solar cells in order to obtain efficient charge carrier extraction for high efficiency.

Original languageEnglish (US)
Pages (from-to)27690-27697
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number41
DOIs
StatePublished - 2015
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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