Oxygen-Induced Degradation in C60-Based Organic Solar Cells: Relation Between Film Properties and Device Performance

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• 作者：João P. Bastos ; Eszter Voroshazi ; Eduard Fron ; Guy Brammertz ; Tim Vangerven ; Mark Van der Auweraer ; Jef Poortmans ; David Cheyns
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：April 20, 2016
• 年：2016
• 卷：8
• 期：15
• 页码：9798-9805
• 全文大小：410K
• 年卷期：0
• ISSN：1944-8252

文摘

Fullerene-based molecules are the archetypical electron-accepting materials for organic photovoltaic devices. A detailed knowledge of the degradation mechanisms that occur in C₆₀ layers will aid in the development of more stable organic solar cells. Here, the impact of storage in air on the optical and electrical properties of C₆₀ is studied in thin films and in devices. Atmospheric exposure induces oxygen-trap states that are 0.19 eV below the LUMO of the fullerene C₆₀. Moreover, oxygen causes a 4-fold decrease of the exciton lifetime in C₆₀ layers, resulting in a 40% drop of short-circuit current from optimized planar heterojunction solar cells. The presence of oxygen-trap states increases the saturation current of the device, resulting in a 20% loss of open-circuit voltage. Design guidelines are outlined to improve air stability for fullerene-containing devices.