Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 46: [DS] Organic electronics and photovoltaics: electronic properties II (jointly with CPP, HL, O)
O 46.1: Vortrag
Mittwoch, 28. März 2012, 11:30–11:45, H 2032
Point of inflection in IV curves due to degradation of cathode-organic interface — •Sidhant Bom, Nivedita Yumnam, and Veit Wagner — Jacobs University Bremen, School of Engineering and Science, Campus Ring 1, 28759 Bremen, Germany
The formation of point of inflection in IV curves is very well known in the field of organic photovoltaics. However, the opinion on this matter is diverse and conflicting. In an attempt to understand this phenomenon, we carried out series of experiments in which we were able to emulate the s-shape in the IV curve. In this study P3HT:PCBM bulk heterojunction solar cells were fabricated in between ITO/PEDOT:PSS and aluminum electrodes. Storing a completely fabricated cell in different environments resulted in a remarkable difference in the degradation of device parameters. Storing in vacuum completely stopped the degradation process while storing in an air tight container with nitrogen ambient showed extreme degradation within 24 hours with a severe s-shape in the IV curve. Interface modification at the cathode by inserting an additional thin C60 layer resulted in a similar s-shaped curve in contrast to the standard device. The data are explained by a model introducing a variable potential barrier at the aluminum cathode.