Compared with liquid electrolytes, the solid polymer electrolyte (SPE), which possesses improved thermal and mechanical stability, is believed the broadest potential application for satisfying the safety needs of advanced electrochemical devices. However, some breakable SPEs could lead to catastrophic failure of batteries that triggered by a short circuit. In the present contribution, a new class of SPE containing disulfide bonds and urea groups is reported. The hydrogen bonding between the urea groups and disulfide metathesis reaction endows the SPE with a high level of self-healing without external stimuli at room temperature as well as ultrafast self-healing at elevated temperatures. The completely healed SPE with extreme damage shows a high self-healing efficiency and no changes in the ionic conductivity and cycling performance of the solid-state lithium-metal/LiFePO4 cell compared to the pristine one.

Generation of high power laser ultrasound strongly demands the advanced materials with efficient laser energy absorption, fast thermal diffusion, and large thermoelastic expansion capabilities. In this study, candle soot nanoparticles-polydimethylsiloxane (CSNPs-PDMS) composite was investigated as the functional layer for an optoacoustic transducer with high-energy conversion efficiency. The mean diameter of the collected candle soot carbon nanoparticles is about 45 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSNPs-PDMS nano-composite laser ultrasound transducer was characterized and compared with transducers using Cr-PDMS, carbon black (CB)-PDMS, and carbon nano-fiber (CNFs)-PDMS composites, respectively. Energy conversion coefficient and À6 dB frequency bandwidth of the CSNPs-PDMS composite laser ultrasound transducer were measured to be 4.41 Â 10 À3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy applications. V

The photoacoustic effect has been broadly applied to generate high frequency and broadband acoustic waves using lasers. However, the efficient conversion from laser energy to acoustic power is required to generate acoustic waves with high intensity acoustic pressure (>10 MPa). In this study, we demonstrated laser generated high intensity acoustic waves using carbon nanofibers–polydimethylsiloxane (CNFs-PDMS) thin films. The average diameter of the CNFs is 132.7 ± 11.2 nm. The thickness of the CNFs film and the CNFs-PDMS composite film is 24.4 ± 1.43 μm and 57.9 ± 2.80 μm, respectively. The maximum acoustic pressure is 12.15 ± 1.35 MPa using a 4.2 mJ, 532 nm Nd:YAG pulsed laser. The maximum acoustic pressure using the CNFs-PDMS composite was found to be 7.6-fold (17.62 dB) higher than using carbon black PDMS films. Furthermore, the calculated optoacoustic energy conversion efficiency K of the prepared CNFs-PDMS composite thin films is 15.6 × 10−3 Pa/(W/m2), which is significantly higher than carbon black-PDMS thin films and other reported carbon nanomaterials, carbon nanostructures, and metal thin films. The demonstrated laser generated high intensity ultrasound source can be useful in ultrasound imaging and therapy.

Despite having attractive stability over the volatile methylammonium (MA) cation, double-cation (Cs, FA) perovskite solar cells are largely overlooked because of their inferior performance compared to MA-based devices. Among all the device engineering strategies, surface passivation represents a promising approach to acquire improved performance. However, effective passivation strategies have not yet been developed for attaining efficiencies of MA-free cells close to their theoretical limit. Herein, fullerene passivators with different binding groups are investigated to establish relationships between molecule structure and perovskite surface properties. It is found that surface treatment with bis-fulleropyrrolidium iodide (bFPI) can have strong interaction with charged defects, leading to effective defect passivation and favorable band-bending at the interface. The resulting bFPI-treated device shows significantly reduced defect density as well as accelerated electron extraction from perovskite into the cathode. Consequently, the MA-free device exhibits an efficiency of 21.1% with long-term environmental stability.

Organic ammonium salts have been widely used for defect passivation to suppress nonradiative charge recombination in perovskite solar cells (PSCs). However, they are prone to form undesirable in-plane favored 2D perovskites with poor charge transport capability that hamper device performance. Herein, the defects passivation role of alkyldiammonium including 1.6-hexamethylenediamine dihydriodide (HDAI 2 ), 1,3-propanediamine dihydriodide (PDAI 2 ), and 1.4-butanediamine dihydriodide (BDAI 2 ) for formamidiniumcesium perovskite is systematically investigated. With help of density functional theory (DFT) calculations, BDA with suitable size can synergistically passivate two defect sites on perovskite surfaces, showing the best defect passivation effect among the above three alkyldiammonium salts. Perovskite films based on BDAI 2 modification are found to keep the 3D perovskite phase with considerably reduced trap-state density, and enhanced carrier extraction. As a result, the BDAI 2 -modified devices deliver impressive efficiencies of 23.1% and 20.9% for inverted PSCs on the rigid and flexible substrates, respectively. Moreover, the corresponding encapsulated rigid devices maintain 92% of the initial efficiency after operating under continuous 1-sun illumination with the maximum power point tracking for 1000 h. Furthermore, the mechanical flexibility of the BDAI 2 -modified flexible device is also improved due to the release of residual stress.

The perovskite solar cells with all-inorganic selective contacts have demonstrated impressive long-term stability and triggered great interests; however, their device performances are still lagging behind their organic counterparts. Here a new design of fullerene-anchored ZnO nanoparticles with low surface defects meets the strict requirements of electron-transporting layer on top of perovskite. Delicate control over surface of oxide nanocrystals also allows the formation of graded heterojunction, and thereby enables the fabrication of p-n dual-sensitized solar cell with high efficiency and stability.

For many years, ultrasound has provided clinicians with an affordable and effective imaging tool for applications ranging from cardiology to obstetrics. Development of microbubble contrast agents over the past several decades has enabled ultrasound to distinguish between blood flow and surrounding tissue. Current clinical practices using microbubble contrast agents rely heavily on user training to evaluate degree of localized perfusion. Advances in separating the signals produced from contrast agents versus surrounding tissue backscatter provide unique opportunities for specialized sensors designed to image microbubbles with higher signal to noise and resolution than previously possible. In this review article, we describe the background principles and recent developments of ultrasound transducer technology for receiving signals produced by contrast agents while rejecting signals arising from soft tissue. This approach relies on transmitting at a low-frequency and receiving microbubble harmonic signals at frequencies many times higher than the transmitted frequency. Design and fabrication of dual-frequency transducers and the extension of recent developments in transducer technology for dual-frequency harmonic imaging are discussed.

Herein, the solid polymer electrolytes (SPEs) were designed and fabricated via the photopolymerization of the macromolecular crosslinker with boronic ester bonds and poly(ethylene glycol) diacrylate (PEGDA) with different molecular weights...