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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]

To improve the comprehensive mechanical properties of Mg-15Al magnesium alloy, different amounts (from 0 to 4.0wt.%) of Nd were added to the alloy and six Mg-15Al-xNd alloys were prepared by metal mould casting. The effect of Nd content on microstructure of the alloys was investigated by means of OM, SEM, EDS, TEM, and XRD. The tensile properties were tested at room temperature (RT) and high temperature (473 K). The results indicate that the primary α-Mg dendrite is significantly refined with the addition of Nd. The best refinement is reached at 1.0wt.% Nd content and the average dendrite arm spacing decreases from 80-100 μm (without Nd addition) to ~20 μm. A further increase in Nd content leads to the coarsening of the primary α-Mg dendrite. The addition of Nd improves the tensile properties of Mg-15Al both at RT and 473 K. The Mg-15Al alloy containing 1.0wt.% Nd exhibits the best tensile properties. Compared with the alloy without Nd, the yield and ultimate tensile strength of the Mg-15Al-1.0Nd alloy at RT increase from 132.3 to 148.6 MPa and 152.3 to 189.6 MPa, increase by 12.3% and 24.5%, respectively; and the elongation at RT increases from 0.05 % to 1.24%. The yield and tensile strength of the alloy at 473 K increase from 97.9 to 115.3 MPa and 121.6 to 140.1 MPa, increase by 15.2% and 20%, respectively. Further increment of Nd content to 1.5wt.% degrades the tensile properties, which is ascribed to grain coarsening and growth of the Al-Nd phase.

Abstract: In the paper, Si element was added in Mg–15Al alloy and processed by the equal channel angular processing (ECAP) for 4 passes using route Bc at 300°C. Microstructure characteristics of experimental alloys before and after ECAP were observed by OM, SEM, EDS and XRD. Tensile test (25, 150 and 200°C) was carried out by a WDW-100KN tensile testing machine. The results show that the grain size of as-cast Mg–15Al alloy was decreased with addition of 1wt% Si element, and new Mg2Si phase formed in the matrix. Meanwhile, network β-Mg17Al12 phases tend to form with the increasing amount of β. After processing by ECAP, the net structure of β-Mg17Al12 phases was disappeared and the morphology was modified. Moreover, the grain size of α-Mg matrix was decreased sharply, from 11.3μm (in Mg–15Al) to 5.98μm (in Mg–15Al–1Si), and Coarse Chinese script Mg2Si phase emerged in Mg–15Al–1Si alloy was broken into particle with dimension of ~3μm by ECAP simultaneously. As a result, the mechanical properties of Mg–15Al–1Si and Mg–15Al alloy were improved by ECAP and the increased amount of Mg–15Al–1Si alloy was greater than that of Mg–15Al, about 51.6MPa in room temperature tensile strength. The Mg2Si phases with high melting were fragmented by ECAP and distributed uniformly in matrix, thus, the mechanical properties of ECAPed Mg–15Al–1Si alloy were more excellent at high temperature, comparing with other experimental alloys. [Copyright &y& Elsevier]