Author/Authors :
Bertho، نويسنده , , Sabine A. Janssen، نويسنده , , Griet and Cleij، نويسنده , , Thomas J. and Conings، نويسنده , , Bert and Moons، نويسنده , , Wouter and Gadisa، نويسنده , , Abay and D’Haen، نويسنده , , Jan and Goovaerts، نويسنده , , Etienne and Lutsen، نويسنده , , Laurence and Manca، نويسنده , , Jean and Vanderzande، نويسنده , , Dirk، نويسنده ,
Abstract :
In high performance polymer:fullerene bulk heterojunction solar cells the nanoscale morphology of interpenetrating acceptor:donor materials is optimized through appropriate preparation conditions such as annealing and choice of solvent, but this initial state-of-the-art morphology will not remain stable during long-term operation. We report the effects of prolonged storage at elevated temperatures on both the morphology and the photovoltaic performance for the model systems MDMO-PPV:PCBM and P3HT:PCBM as compared to ‘High Tg PPV’:PCBM based solar cells, where the ‘High Tg PPV’ is characterized by its high glass transition temperature (138 °C). In situ monitoring of the photocurrent–voltage characteristics at elevated temperatures, in combination with a systematic transmission electron microscopy (TEM) study and complementary optical spectroscopy, reveals distinct degradation kinetics and morphological changes that indicate the occurrence of different underlying physico-chemical mechanisms.
Keywords :
Organic Photovoltaics , thermal stability , glass transition temperature , morphology
