Substituent effect on the π linkers in triphenylamine dyes for sensitized solar cells: a DFT/TDDFT study.

A series of metal-free organic donor-π bridge-acceptor dyes are studied computationally using density functional theory (DFT) and time-dependent DFT (TDDFT) approaches to explore their potential performances in dye-sensitized solar cells (DSSCs). Taking triphenylamine (TPA) and cyanoacrylic acid moieties as donor and acceptor units, respectively, the effects of different substituents of the π linkers in the TPA-based dyes on the energy conversion efficiency of the DSSCs are theoretically evaluated through optimized geometries, charge distributions, electronic structures, simulated absorption spectra, and free energies of injection. The results show that the molecular orbital energy levels and electron-injection driving forces of the TPA dyes can be tuned by the introduction of substituents with different electron-withdrawing or -donating abilities. The electron-withdrawing substituent always lowers the energies of both frontier orbitals, while the electron-donating one heightens them simultaneously. The efficiency trend of these TPA derivatives as sensitizers in DSSCs is also predicted by analyzing the light-harvesting efficiencies and the free energies of injection. The following substituents are shown to increase the efficiency of the dye: OMe, OEt, OHe, and OH.

Flexible MXene/Bacterial Cellulose Film Sound Detector Based on Piezoresistive Sensing Mechanism.

Flexible pressure sensors have aroused extensive attention in health monitoring, human-computer interaction, soft robotics, and more, as a staple member of wearable electronics. However, a majority of traditional research focuses solely on foundational mechanical sensing tests and ordinary human-motion monitoring, ignoring its other applications in daily life. In this work, a paper-based pressure sensor is prepared by using MXene/bacterial cellulose film with three-dimensional isolation layer structure, and its sensing capability as a wearable sound detector has also been studied. The as-prepared device exhibits great comprehensive mechanical sensing performance as well as accurate detection of human physiological signals. As a sound detector, not only can it recognize different voice signals and sound attributes by monitoring movement of throat muscles, but also it will distinguish a variety of natural sounds through air pressure waves caused by sound transmission (also called sound waves), like the eardrum. Besides, it plays an important role in sound visualization technology because of the ability for capturing and presenting music signals. Moreover, millimeter-scale thickness, lightweight, and degradable raw materials make the sensor convenient and easy to carry, meeting requirements of environmental protection as well.

Preparation and characterization of solvent-free fluids reinforced and plasticized polylactic acid fibrous membrane.

In this paper, the electronspun Polylactic acid (PLA)/TiO2 nanofluids (nfs) fibrous membrane with good toughness, hydrophilicity and antibacterial activities are fabricated by taking full advantages of solvent-free TiO2 nfs with amphiphilicity and ionic conductivity. The resulting PLA/TiO2 nfs fibrous membrane exhibits excellent mechanical performance with a tensile strength and elongation at break of 3.68 MPa and 97.32 MPa at 5 wt% loading, respectively, which is 4 and 8 times higher than that of pure PLA, respectively. Additionally, TiO2 nfs can migrate onto the surface of PLA fibers during electrospun process, which significantly enhanced hydrophilicity, antistatic property, moisture sorption capacity and wicking properties of PLA fabrics. Meanwhile, the membrane also showed ultrafast water filtration of 3500 L m-2 h-1 driven by gravity force, which is 10-12 times higher than that of commercial ultrafiltration membrane. After ion-exchange reaction with salt solution, excellent antibacterial activity (against E. coli and S. aureus was 95% and 99.9%, respectively) and separation efficiency (above 90% on E. coli) of the obtained fabrics are also achieved. Overall, organic nfs are an idea candidate for fabricating hydrophilic PLA based biodegradable fabric that can be applied in contaminated water treatment, antibacterial textiles and biodegradable absorption materials.