Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 13: Poster Session I

HL 13.61: Poster

Montag, 12. März 2018, 17:30–19:30, Poster B

Degradation mechanism in high performance PffBT4T-2OD:PC71BM organic devices — •Joshua Kreß and Andreas Weu — Centre for Advanced Materials, Heidelberg, Deutschland

Although in recent years significant progress has been made in improving the performance of organic photovoltaic devices, their environmental stability remains a limiting factor preventing their integration in industrial applications. We investigate the degradation mechanisms of high performance photovoltaic devices based on PffBT4T-2OD:PC71BM which result in record power conversion efficiencies of 11%. To identify the contribution of the deterioration of charge transport during degradation to the photovoltaic performance loss, the active layers of the photovoltaic devices have been investigated in bottom-gate/top-contact field effect transistors (OFETs) which have been degraded under identical conditions to complete photovoltaic devices. The studies are combined with x-ray photoemission spectroscopy (XPS), photothermal deflection spectroscopy (PDS) and transient absorption spectroscopy (TA). We compare the effects of exposure to nitrogen or oxygen with and without light and find that exposure to oxygen alone (in dark) results in a similar degradation of the photovoltaic performance as that caused by exposure to light (in inert atmosphere). Despite this, the effect on charge transport is very different and is a consequence of oxygen induced p-doping of the active layer. This highlights the importance of identifying the individual causes of degradation introduced by the various environmental factors in order to be able to develop relevant mitigation strategies.