Search

Intrinsically stretchable organic photovoltaic cells (OPVs) have garnered significant attention as crucial devices for powering next‐generation wearable electronics. Despite the rapid power conversion efficiency gains in champion OPVs, their brittle stretchability has failed to meet the demands of the Internet of Things era, severely hindering further development and practical applications. In this regard, a new dual‐donor polymer blending strategy is demonstrated for constructing intrinsically stretchable OPVs by designing a novel high‐molecular–weight conjugated polymer PM6‐HD. This PM6 derivative featuring long alkyl chains can reach a sufficiently high molecular weight and thus exhibits a high fracture strain exceeding 90%, which is ≈12 times higher than the benchmark PM6. Synergistic optimization of mechanical properties and photovoltaic performance in polymer:small molecule and all‐polymer systems constructed from the physical blends of PM6 and PM6‐HD is achieved. Crucially, the resulting intrinsically stretchable OPV demonstrates excellent stretchability and stability, with a record PCE80% strain of 50.3% and the efficiency retention of above 80% even after 1000 cycles of cyclic stretching at high strains. This work contributes to the advancement of intrinsically stretchable OPV technology and opens up new possibilities for its integration into wearable electronic devices. [ABSTRACT FROM AUTHOR]

All‐polymer solar cells (all‐PSCs) are one of the most promising application‐oriented organic photovoltaic technologies due to their excellent operational and mechanical stability. However, the power conversion efficiencies (PCEs) are mostly lower than 16%, restricting their core competitiveness. Furthermore, the improvement of mechanical durability is rarely paid attention to cutting‐edge all‐PSCs. This work deploys a low‐cost "technical grade" PCBM (incompletely separated but pure mixtures containing ≥90% [70]PCBM or [60]PCBM), into the efficient PM6:PY‐IT all‐polymer blend, successfully yielding a high‐performance ternary device with 16.16% PCE, among the highest PCE values for all‐PSCs. Meanwhile, an excellent mechanical property (i.e., crack onset strain = 11.1%) promoted from 9.5% for the ternary system is also demonstrated. The "technical grade" PCBM slightly disrupts the crystallization of polymers, and disperses well into the amorphous polymer regions of the all‐PSC blends, thus facilitating charge transport and improving film ductility simultaneously. All these results confirm introducing low‐cost "technical grade" PCBM with high electron mobility into all‐polymer blends can improve carrier mobility, reduce charge recombination, and optimize morphology of the amorphous polymer regions, thus yielding more efficient and mechanically durable all‐PSCs. [ABSTRACT FROM AUTHOR]

• CB particles were decorated on PDMS foam to fabricate a flexible porous piezoresistive sensor. • The sensor possesses a very high linear working range (up to 91%). • A fast response time (45 ms) and superior durability (>15000 cycles) have both been achieved. • The sensor possess an excellent hydrophobic property (water contact angle up to 149°). • The CB/PDMS foam can also be used for oil/water separation. The achievement of favorable pressure sensor integrated with large linear working range, high sensitivity and excellent response durability is still a great challenge for flexible and wearable piezoresistive materials. In this paper, a facile and scalable strategy is proposed to fabricate a porous foam sensor based on carbon black/polydimethylsiloxane (CB/PDMS). CB particles were decorated onto the surface of the cell walls and some particles were embedded into PDMS matrix after the ultrasonication treatment. The density and porosity of the foam are 0.13 g/cm3 and 76.1%, respectively. A very high linear working range (up to 91%), an excellent response stability, a fast response time (45 ms), and a superior durability (>15000 cycles) are achieved synchronously. Here, the large linear sensing range is mainly related to the nice CB conductive network on the cross-linked PDMS foam and the high modulus and elasticity of the composite material, which ensure the homogeneous deformation of the foam under compression. It is worth noting that the response behavior of CB/PDMS foam is maintained well even in water owing to its excellent hydrophobic property (water contact angle up to 149°), indicating that this material can be used as a waterproof piezoresistive sensor. Our CB/PDMS foam is then assembled as a wearable sensor, and it exhibits nice capability of monitoring human body motions, such as the bending of fingers and elbow, walking, jumping and squatting, etc. The porous foam sensor also has a good oil/water separation ability, showing a multifunctional characteristic. [ABSTRACT FROM AUTHOR]