Unraveling the Correlations between Mechanical Properties, Miscibility, and Film Microstructure in All-Polymer Photovoltaic Cells

摘要

The rapid development of low bandgap polymer acceptors has promoted theefficiency up to ≈17% for all-polymer solar cells (all-PSCs). Nevertheless, thepolymeric blend film, core to the photoelectric conversion of all-PSCs, has notbeen thoroughly understood in terms of the influence and regulatory factorsof mechanical properties, which hinders the advances in flexible and wearableapplications. Herein, a range of characterization methods is combined to investigatethe mechanical properties, miscibility, and film microstructure of theblends based on several representative polymer donors (PTzBI-Si, PTVT-T, PM6and PTQ10) and a benchmark polymer acceptor N2200, and to further revealthe miscibility-property relationships of the miscibility property. The resultsstress that fracture behaviors and elastic moduli of these blends with variedcompositions show different changing trends, which are affected by molecularinteractions and aggregated structure of the blends. The elastic moduli of thefour all-polymer blends can be nicely predicted by different models that arededuced from macromolecular mechanics. Most crucially, the correlationsbetween elastic modulus, morphology, and miscibility of all-polymer blendsare elucidated for the first time. The derived relationships is validated withanother high-efficiency blend and will be the key to the successful fabricationof mechanically robust and stretchable all-PSCs with high efficiency.