The combination of mass-production compatible coating techniques and environmentally friendly solvents to process bulk heterojunction solar cells represents a key issue to scale up this technology. In this work we demonstrate that using a benchmark polymer HBG-1 blended with PC61BM, the replacement of a common chlorinated processing solvent (orthodichlorobenzene) with a non-chlorinated analogous (o-xylene) not only allows the fabrication of blade-coated bulk heterojunction devices with identical photovoltaic performance, but also determines a great enhancement of the resulting thermal stability. Thermal degradation tests were carried out in inert atmosphere, by keeping the solar cells onto a hot plate at 85 °C and monitoring their OPV performance. In parallel, the morphological changes of the active layers induced by thermal stress are investigated by combining two complementary light-based imaging techniques, laser scanning confocal and photocurrent microscopy, which offer the great advantage to simultaneously study on complete devices the blend morphology and the electrical properties, point-by-point, of the active layer even in regions unlikely accessible (e.g. the active area under the top electrode) using other techniques. As a result, we found that solar cells processed from a non-chlorinated based solvent, in comparison to an analogous reference system, exhibit a different evolution of the resulting BHJ morphology during thermal ageing, in perfect agreement with the corresponding photovoltaic responses.
Bolognesi, M., Prosa, M., Tessarolo, M., Donati, G., Toffanin, S., Muccini, M., et al. (2016). Impact of environmentally friendly processing on polymer solar cells: Performance, thermal stability and morphological study by imaging techniques. SOLAR ENERGY MATERIALS AND SOLAR CELLS, 155, 436-445 [10.1016/j.solmat.2016.06.044].
Impact of environmentally friendly processing on polymer solar cells: Performance, thermal stability and morphological study by imaging techniques
TESSAROLO, MARTA;
2016
Abstract
The combination of mass-production compatible coating techniques and environmentally friendly solvents to process bulk heterojunction solar cells represents a key issue to scale up this technology. In this work we demonstrate that using a benchmark polymer HBG-1 blended with PC61BM, the replacement of a common chlorinated processing solvent (orthodichlorobenzene) with a non-chlorinated analogous (o-xylene) not only allows the fabrication of blade-coated bulk heterojunction devices with identical photovoltaic performance, but also determines a great enhancement of the resulting thermal stability. Thermal degradation tests were carried out in inert atmosphere, by keeping the solar cells onto a hot plate at 85 °C and monitoring their OPV performance. In parallel, the morphological changes of the active layers induced by thermal stress are investigated by combining two complementary light-based imaging techniques, laser scanning confocal and photocurrent microscopy, which offer the great advantage to simultaneously study on complete devices the blend morphology and the electrical properties, point-by-point, of the active layer even in regions unlikely accessible (e.g. the active area under the top electrode) using other techniques. As a result, we found that solar cells processed from a non-chlorinated based solvent, in comparison to an analogous reference system, exhibit a different evolution of the resulting BHJ morphology during thermal ageing, in perfect agreement with the corresponding photovoltaic responses.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.