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Four-dimensional printing refers to a process through which a 3D printed object transforms from one structure into another through the influence of an external energy input. Self-folding structures have been extensively studied to advance 3D printing technology into 4D using stimuli-responsive polymers. Designing and applying self-folding structures requires an understanding of the material properties so that the structural designs can be tailored to the targeted applications. Poly(N-iso-propylacrylamide) (PNIPAM) was used as the thermo-responsive material in this study to 3D print hydrogel samples that can bend or fold with temperature changes. A double-layer printed structure, with PNIPAM as the self-folding layer and polyethylene glycol (PEG) as the supporting layer, provided the mechanical robustness and overall flexibility to accommodate geometric changes. The mechanical properties of the multi-material 3D printing were tested to confirm the contribution of the PEG support to the double-layer system. The desired folding of the structures, as a response to temperature changes, was obtained by adding kirigami-inspired cuts to the design. An excellent shape-shifting capability was obtained by tuning the design. The experimental observations were supported by COMSOL Multiphysics® software simulations, predicting the control over the folding of the double-layer systems. [ABSTRACT FROM AUTHOR]

In organic solar cells (OSCs), improving the properties at the interface of the bulk heterojunction (BHJ) photoactive layer and the buffer layer is desired, but achieving a high-quality interface between these two layers is inevitably challenging. Herein, a novel (PC61BM)-doped zinc oxide, that is, a (PC61BMZnO) DEZ hybrid thin film, is proposed for application as a cathode buffer layer (CBL) for OSCs based on both fullerene-based acceptors and nonfullerene acceptors. These thin films require low annealing temperatures and can be deposited via a one-step solution-processable method using a hybrid precursor composed of PC61BM and diethylzinc solution (DEZ). The study reveals that the performance of devices with (PC61BM-ZnO)DEZ hybrid thin films as a CBL exceeds that of devices with thin films of conventional ZnO as a CBL. Impedance analysis of the fabricated OSCs suggests improved charge collection efficiency in the devices with (PC61BM-ZnO)DEZ thin film. Optical, electrical, morphological, and compositional characterizations of thin films used as CBLs confirm the presence of a PC61BM-rich phase with traces of d-C61 (fullerene dimer) at the surface of the hybrid (PC61BM-ZnO)DEZ thin film. These phases help in tuning the interfacial properties by ensuring better coupling between the BHJ photoactive layer and the CBL. [ABSTRACT FROM AUTHOR]

The article discusses the synthesis of fullerene and arene ruthenium moieties by focusing on the merger of the carbon molecule and ruthenium complexes tested by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. The article also provides characterization of the carbon molecule and arene ruthenium complexes.