Elemental mapping of interfacial layers at the cathode of organic solar cells

Gopal K. Mor, Thinh P. Le, Kiarash Vakhshouri, Derek R. Kozub, Enrique Daniel Gomez

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

One of the limitations in understanding the performance of organic solar cells has been the unclear picture of morphology and interfacial layers developed at the active layer/cathode interface. Here, by utilizing the shadow-Focused Ion Beam technique to enable energy-filtered transmission electron microscopy imaging in conjunction with X-ray photoelectron spectroscopy (XPS) experiments, we examine the cross-section of polythiophene/fullerene solar cells to characterize interfacial layers near the semiconductor-cathode interface. Elemental mapping reveals that localization of fullerene to the anode interface leads to low fill factors and S-shaped current - voltage characteristics. Furthermore, the combination of elemental mapping and XPS depth profiles of devices demonstrate oxidation of the aluminum cathode at the active layer interface for devices without S-shaped characteristics and fill factors of 0.6. The presence of a thin dielectric at the semiconductor-cathode interface could minimize electronic barriers for charge extraction by preventing interfacial charge reorganization and bandbending. (Chemical Equation Presented).

Original languageEnglish (US)
Pages (from-to)19638-19643
Number of pages6
JournalACS Applied Materials and Interfaces
Volume6
Issue number22
DOIs
StatePublished - Nov 26 2014

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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