Effect of light induced degradation on electrical transport and charge extraction in polythiophene:Fullerene (P3HT:PCBM) solar cells

Autor: Fortunato Piersimoni, Henk Vrielinck, Tom Aernouts, Johan Lauwaert, Donato Spoltore, Sabine Bertho, Jean Manca, Samira Khelifi, Marc Burgelman, Eszter Voroshazi
Rok vydání: 2014
Předmět:
Zdroj: Solar Energy Materials and Solar Cells. 120:244-252
ISSN: 0927-0248
DOI: 10.1016/j.solmat.2013.09.010
Popis: We investigate the photodegradation in inert atmosphere of (poly 3-hexylthiophene:[6,6]-phenyl-C61-butyric acid methyl ester) (P3HT:PCBM) heterojunction solar cells under continuous illumination using advanced electrical characterization and a device modeling tool. Our results indicate that different failure mechanisms contribute to the performance loss. The first 250 h of illumination induced p-type doping and recombination related to traps in the blend which mainly decreases the short-circuit current and the efficiency of the cells. Device modeling and simulation allowed us to prove that increased p-type doping of the blend provoke the loss in the short-circuit current and the quantum efficiency by simultaneous reduction of charge carrier mobility and the electric field together with a shrink of the space charge region. Transmission electron microscopy (TEM) measurements reveal a change in the blend morphology upon long illumination times manifested by phase segregation in the blend. The reduction in the open-circuit voltage is reported to be related to a slight reduction of the charge transfer energy (CT) upon 700 h of illumination aging. The final failure mechanism was a rapid drop in the fill factor which occurs upon 1000 h of illumination and manifested by the appearance of an S-shape J–V characteristic. This failure mechanism is linked to the reduction of charge extraction caused by a reduced surface recombination velocity at the contacts.
Databáze: OpenAIRE
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