In the past two decades, various research works have been conducted in the field of flexible electronic devices (FEDs). Researchers have focused their efforts on solving the existing challenges in the electronic, electrochemical, and mechanical behaviors of FEDs. The importance of flexible lithium-ion batteries (FLIBs) in the area of FEDs is evident; however, less attention has been paid to the mechanical behavior of FLIBs in comparison with the material and electrochemical characteristics. The present paper reviewed the research works in the FLIBs, focusing on their mechanical integrity and electrochemical performances. First, an introduction to FLIBs was presented, and the previous review papers published in this field were briefly introduced. Then, a detailed review of the available electrochemical and mechanical research works on FLIBs was presented. Moreover, the mechanical testing methods (tensile, compressive, indentation, fatigue, and adhesion) for the characterization of FLIBs’ components, the research works on the simulation and modeling of the mechanical behavior of FLIBs, and a summary of the present situation and the future trend of research in this field were reviewed and presented.

The slot-die coating is recognized as the most compatible method for the roll-to-roll (R2R) processing of large-area flexible organic solar cells (OSCs). However, the photovoltaic performance of the large-area flexible all-polymer solar cells was significantly lagging behind that of polymer donors with small molecule non-fullerene acceptors devices. In this work, the 1 cm² flexible device of an all-polymer system, PTQ10:PYF-T-o, fabricated by slot-die coating, achieves an excellent efficiency of 11.24% via controlling the coating temperatures. It is found that, compared with the donor, the crystallinity of PYF-T-o plays a crucial role in device performance. The all-polymer flexible devices show superior mechanical bending stability, maintaining an efficiency of over 95% of the initial value during a 1000-cycle bending test.

Halogenated thiophenes are generally used units for constructing organic semiconductor materials for photovoltaic applications. Here, we introduced thiophene, 2-bromothiophene, and 2-chlorothiophene units to the central core of quinoxaline-based acceptors and obtained three acceptors, Qx-H, Qx-Br, and Qx-Cl, respectively. Compared with Qx-H, Qx-Br and Qx-Cl showed enhanced absorption, down-shifted energy levels, improved crystallinity, and reduced energy disorder. The improved crystallinity significantly optimized the blend morphology, leading to efficient charge generation and transport and, therefore, less bimolecular recombination. Eventually, PM6:Qx-Br-based devices exhibited an outstanding power conversion efficiency of 17.42% with a high open-circuit voltage (V_OC) of 0.915 V. Furthermore, Y6 was introduced into the PM6:Qx-Br binary system to improve the light utilization, and the resulting ternary devices delivered a high PCE of 18.36%. This study demonstrated the great potential of halogenated thiophene substitution in quinoxaline-based acceptors for building high-performance organic solar cell acceptor materials.

Small-molecule organic solar cell is a category of clean energy potential device since charge transfers between donor and acceptor. The morphologies, co-assembly behavior, interaction sites, and charge transfer of BTID-nF (n = 1, 2)/PC₇₁BM donor–acceptor system in the active layer of organic solar cell have been studied employing scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), density functional theory (DFT) calculations, and transient absorption (TA) spectroscopy. The results show that BTID-1F and BTID-2F form bright strip structures, whereas BTID-nF (n = 1, 2)/PC₇₁BM form ridge-like structures with each complex composed of one BTID-nF (n = 1, 2) molecule and four PC₇₁BM molecules which adsorbed around the BTID-nF (n = 1, 2) molecule by S···π interaction. With the assistance of S···π interaction between BTID-nF (n = 1, 2) and PC₇₁BM, BTID-nF (n = 1, 2)/PC₇₁BM co-assembled ridge-like structures are more stable than the BTID-nF (n = 1, 2) ridge structures. To investigate the charge transfer of BTID-nF (n = 1, 2)/PC₇₁BM system, STS measurements, DFT calculation, and TA spectroscopy are further performed. The results show that charge transfer occurs in BTID-nF (n = 1, 2)/PC₇₁BM system with the electron transferring from BTID-nF (n = 1, 2) molecules to PC₇₁BM.

Conducting polymer actuators that can undergo complex and coordinated motions are generally obtained by using complex microfabrication methods to pattern several conducting polymer components. Herein, we describe a facile approach for fabricating electromagnetic synergetic actuators based on polypyrrole/Fe₃O₄ hybrid nanotube arrays. The actuator can perform biomimetic movements like arm-hand coordination. In this case, a magnetic field is used for primary actuation like an arm, i.e., large-scale angular movement, and an electric potential is used for secondary adjustment like a hand, i.e., small-scale angular movement.