Highly Skin-Compliant Polymeric Electrodes with Synergistically Boosted Conductivity toward Wearable Health Monitoring.

Despite rapid advances in stretchable electrodes, successful examples of polymeric dry electrodes are limited. Especially in wearable health monitoring, it is urgent to develop biocompatible electrodes that possess intrinsic skin-compliance while maintaining a high conductivity. Herein, a strategy is demonstrated to synergistically regulate the interpenetration behavior and molecular crystallinity in the blend via embedding a novel double network, i.e. physically cross-linked poly(vinyl alcohol) (PVA) and covalently cross-linked polyethylene glycol diacrylate (PEGDA), into the PEDOT:PSS matrix. The favorable interaction energy between PVA and PEGDA enables well-distributed microstructure with finer phase separation in the film, affording a low Young's modulus of 16 MPa with a high conductivity of 442 S/cm. Consequently, the optimal polymeric electrode can acquire high-quality electromyogram (EMG) and electrocardiogram (ECG) signals. Our results provide a feasible approach for producing skin-compliant polymeric electrodes toward next-generation health monitors.

A "σ-Hole"-Containing Volatile Solid Additive Enabling 16.5% Efficiency Organic Solar Cells.

Here we introduce a σ-hole-containing volatile solid additive, 1, 4-diiodotetrafluorobenzene (A3), in PM6:Y6-based OSCs. Aside from the appropriate volatility of A3 additive, the synergetic halogen interactions between A3 and photoactive matrix contribute to more condensed and ordered molecular arrangement in the favorable interpenetrating donor/acceptor domains. As a result, greatly accelerated charge transport process with suppressed charge recombination possibility is observed and ultimately a champion PCE value of 16.5% is achieved. Notably, the A3 treated OSCs can maintain a high efficiency of over 16.0% in a wide concentration range of A3 additive between 10 and 35 mg/mL. The A3-treated device shows excellent stability with an efficiency of 15.9% after 360-h storage. This work demonstrates that the σ-hole interaction can be applied to enhance the OSC performance and highlights the importance of non-covalent interactions in the optoelectronic materials.