Unlocking Intrinsic Stretchability in PM6-Based Materials for Next-Generation Solar Cells: Challenges and Innovations
Intrinsically stretchable organic solar cells (IS-OSCs) are critical for wearable and portable power, yet state-of-the-art PM6-based active layers exhibit fracture strains below 8% and high elastic modulus due to rigid conjugated backbones. This tutorial review systematically examines strategies to enhance mechanical resilience while preserving photovoltaic performance. We analyze third-component incorporation—guest polymer donors/acceptors and insulating polymers—as a primary route to improve stretchability, with specific examples achieving crack-onset strain (COS) exceeding 40% via flexible spacer-block multi-component copolymerized donors (Energy Environ Sci, 2024, 17: 9359–9374). Structural design of PM6 aimed at reducing backbone rigidity is discussed, including non-covalent interactions with polyvinyl chloride that yield excellent mechanical properties and stability (Angew Chem Int Ed, 2023, 62: e202312357). Predictive models for mechanical properties are summarized, encompassing modulus, COS, and fracture strain. Recent advances report mechanically robust OSCs with 19% efficiency (Adv Mater, 2024, 36: 2312805) and certified flexible organic photovoltaics beyond 19% via synergistic multimodal energy dissipation (Adv Mater, 2025, 37: 2411989). Insulating polymer-mediated stability and performance are shown to depend on molecular weight (Adv Funct Mater, 2024, 34: 2408340). The review concludes with future challenges and perspectives for stretchy OSCs, emphasizing the trade-off between efficiency and mechanical robustness.