The formation of interfacial wrinkles at the metal contacts on organic thin films

• Published in: Thin solid films 2014-04, Vol.556, p.294-299
• Main Authors: Fang, Jian-Jhih, Tsai, Huai-Wen, Ni, I-Chi, Tzeng, Shien-Der, Chen, Mei-Hsin
• Format: Article
• Language: English
• Subjects: Compressive strain; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Interfaces; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Mechanical and acoustical properties; Morphology; Organic photovoltaics; Physical properties of thin films, nonelectronic; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermal properties of condensed matter; Thermal properties of small particles, nanocrystals, nanotubes; Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2014.01.038

The basic mechanism leading to the morphology change in the active layer was explored systematically. We found that the wrinkles appearing at the cathode surface under post-annealing processes are more prominent than those under pre-annealing processes, which is strongly related to the roughness increase of the active layer. Due to thermal-induced instability from the aluminum (Al) layer with the device under post-annealing processes, a net compressive strain develops from the thermal expansion mismatch between the layers. Furthermore, an analysis of the mechanical properties shows that the enlarged nano-dimension roughness of the active layer is dominated by the final-bottom morphology of the compressed Al layer which depends on the annealing sequence. •The wrinkles are more prominent under post-annealing process.•The mismatch of thermal expansion coefficients causes the net compressive strain.•The roughness of the active layer is dominated by the compressed aluminum layer.