Film stresses and electrode buckling in organic solar cells

Brand, Vitali; Levi, Kemal; McGehee, Michae D.; Dauskardt, Reinhold H.

Film stresses and electrode buckling in organic solar cells

Type

Article

Authors

Brand, Vitali
Levi, Kemal
McGehee, Michae D.
Dauskardt, Reinhold H.

KAUST Grant Number

KUS-C1-015-21

Date

2012-08

Abstract

We investigate the film stresses that develop in the polymer films and metal electrodes of poly(3-hexyl thiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction (BHJ) organic solar cells. A compressive biaxial stress of ∼-36 MPa was measured in PEDOT:PSS while a tensile stress of ∼6 MPa was measured in the BHJ layer. We then analyze the effect of electrode deposition rate on the film stresses in the Al electrode. Compressive stresses of ∼-100 to -145 MPa in the Al electrode lead to a buckling instability resulting in undulating electrode surface topography. The BHJ layer was found to have the lowest cohesion (∼1.5-1.8 J/m 2) among the layers of the solar cell and dependent on the Al electrode deposition rate. The cohesive failure path in the BHJ layer exhibited the same periodicity and orientation of the Al electrode buckling topography. We discuss the implications of the film stresses on damage processes during device fabrication and operation. © 2012 Elsevier B.V. All rights reserved.

Citation

Brand V, Levi K, McGehee MD, Dauskardt RH (2012) Film stresses and electrode buckling in organic solar cells. Solar Energy Materials and Solar Cells 103: 80–85. Available: http://dx.doi.org/10.1016/j.solmat.2012.04.003.

Acknowledgements

This work was partly supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Materials Sciences Division of the US Department of Energy, under Contract no. DE-FG02-07ER46391 and by the Center for Advanced Molecular Photovoltaics (CAMP) supported by King Abdullah University of Science and Technology (KAUST) under Award no. KUS-C1-015-21.