The effect of barrier performance on the lifetime of small-molecule organic solar cells

Journal article

In this work, we use different encapsulations to protect vacuum-evaporated small molecule organic solar cells with a simple p-i-i-stack for lifetime studies. Our devices use ZnPc and C60 as active materials. Lifetimes (T50) in a range from 300 h for un-encapsulated devices to 4000 h for glass-encapsulated have been observed. We use a model to distinguish between the water vapor transmission rate (WVTR) of the barrier and an additional WVTR of the aluminum top electrode. For all observed devices a loss of 50% of initial efficiency is observed when 10 mg m⁻² water entered the device. The losses are related to a reduction of short circuit current density only, whereas open circuit voltage and fill factor remains unaffected. We relate this to an interaction of the water molecules with C60. © 2011 Elsevier B.V.

Authors: Hermenau, M; Schubert, S; Klumbies, H; Fahlteich, J; Müller-Meskamp, L

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Solar Energy Materials and Solar Cells
• Volume: 97
• Pages: 102-108
• Publication date: 2012-02-01
• DOI: 10.1016/j.solmat.2011.09.026
• ISSN: 0927-0248
• Language: English
• Keywords: Lifetime; Organic solar cell; WVTR; Small molecule; Degradation; Encapsulation