Light Absorption in Organic Thin Films: The Importance of Oriented Molecules

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• 作者：Olga Guskova ; Christoph Sch眉nemann ; Klaus-Jochen Eichhorn ; Karsten Walzer ; Marieta Levichkova ; Steffen Grundmann ; Jens-Uwe Sommer
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：August 22, 2013
• 年：2013
• 卷：117
• 期：33
• 页码：17285-17293
• 全文大小：584K
• 年卷期：v.117,no.33(August 22, 2013)
• ISSN：1932-7455

文摘

In this work we apply a joint experimental and theoretical approach to investigate thin films of side chain substituted dicyanovinyl quaterthiophenes (DCV4T-Et2) and DCV4T-Et2:C60 blends, prototypic absorbers for small molecule organic solar cells. Structural characterization of the morphology of thin films thermally deposited at different substrate temperatures on a silica surface was performed by variable angle spectroscopic ellipsometry, grazing incidence X-ray diffraction, and atomic force microscopy measurements. These methods, combined with full-atomistic molecular dynamic (MD) simulation, provide detailed information about thin film morphology, namely about molecular orientation, absorption, phase separation, and crystallinity, i.e., factors that affect the efficiency of organic solar cells. Using molecular dynamics simulation, we can constitute why the DCV4T-Et2 molecules arrange strongly tilted in pristine (69掳 to 70掳 tilt angle to the substrate normal) and DCV4T-Et2:C60 blend films (tilt angle of 65掳 to 69掳).