Cohesion and device reliability in organic bulk heterojunction photovoltaic cells

Vitali Brand, Christopher Bruner, Reinhold H. Dauskardt

Research output: Contribution to journalArticlepeer-review

79 Scopus citations

Abstract

The fracture resistance of P3HT:PC 60BM-based photovoltaic devices are characterized using quantitative adhesion and cohesion metrologies that allow identification of the weakest layer or interface in the device structure. We demonstrate that the phase separated bulk heterojunction layer is the weakest layer and report quantitative cohesion values which ranged from ∼1 to 20 J m -2. The effects of layer thickness, composition, and annealing treatments on layer cohesion are investigated. Using depth profiling and X-ray photoelectron spectroscopy on the resulting fracture surfaces, we examine the gradient of molecular components through the thickness of the bulk heterojunction layer. Finally, using atomic force microscopy we show how the topography of the failure path is related to buckling of the metal electrode and how it develops with annealing. The research provides new insights on how the molecular design, structure and composition affect the cohesive properties of organic photovoltaics. © 2011 Elsevier B.V. All rights reserved.
Original languageEnglish (US)
Pages (from-to)182-189
Number of pages8
JournalSolar Energy Materials and Solar Cells
Volume99
DOIs
StatePublished - Apr 2012
Externally publishedYes

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