The role of thermal cycling of inverted P3HT:PCBM-based polymer solar cells is reported. We found that thermal cycling between -40 °C and 85 °C up to 200 cycles had no significant effect on solar cell efficiency and mechanical integrity. On the contrary, the solar cells exhibited a slight increase in fracture resistance, similar to that reported for a post-electrode deposition thermal annealing at 85 °C. Gc increased from 2.6 J/m2 for our control solar cells to a sustained maximum value of 4.0 J/m2 after 25 thermal cycles. Surface analysis on the fractured samples revealed the formation of an intermixed layer between P3HT:PCBM and PEDOT:PSS, causing the debond path to change from adhesive between P3HT:PCBM and PEDOT:PSS to meandering through the intermixed layer. A kinetic analysis was used to model the effect of thermal cycling on the Gc values of polymer cells. The model revealed for cycling between -40 °C and 85 °C that 25 cycles are needed to reach the maximum Gc, which is consistent with our experimental results. After 5 thermal cycles, the effects of heating and cooling have little impact on the mechanical stability of polymer solar cells.
Bibliographical noteKAUST Repository Item: Exported on 2021-11-04
Acknowledged KAUST grant number(s): KUS-C1-015-21
Acknowledgements: This research was supported by the Center for Advanced Molecular Photovoltaics (CAMP) supported by King Abdullah University of Science and Technology (KAUST) under Award no. KUS-C1-015-21. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.