An unconventional route to an ambipolar azaheterocycle and its in situ generated radical anion.

Herein we report the synthesis, characterization and application of an azaheterocycle 4 obtained via an unprecedented C-N coupling. The neutral azaheterocycle undergoes one-electron reduction to form an air-stable radical anion in situ, which provides added benefit towards operational stability of the device during n-type charge transport. The unusual stability of this radical anion is due to the fact that the fused cyclopentane ring upon reduction forms aromatic cyclopentadienyl anion, and the negative charge delocalizes over the nearly planar azaheterocycle core. The present azaheterocycle can be considered as a mimic of a fullerene fragment, which shows balanced ambipolar charge transport in space charge limited current (SCLC) devices with moderate hole (µh) and electron (µe) mobilities (µh = 2.96 × 10-3 cm2 V-1 s-1 and µe = 1.11 × 10-4 cm2 V-1 s-1). Theoretical studies such as nucleus independent chemical shifts (NICS) calculations, anisotropy of the induced current density (ACID) plots, spin density mapping and anisotropic mobility calculations were performed to corroborate the experimental findings.

Wearable Sensing Devices for Point of Care Diagnostics.

The growth of smart wearable sensing systems has gained immense importance in the present mode of data acquisition and signaling in pharmaceutical, healthcare, and wellness industries. Presently, application of smart wearables is gaining prominence in several fitness activities, therapeutics, and diagnostic areas. Smart wearable biosensors offer real-time monitoring of physiological metrics and biomarkers that are specific to certain diseases in ambulant condition. This review offers a broad overview of the state-of-the-art progress on smart wearable biosensors focusing on applications in point of care diagnostics. A careful comparison of presently available commercial devices, implementation in clinical trials, and validation also have been highlighted in the present review. This work concludes with challenges and future prospects for scientists and engineers working in the nascent interdisciplinary field.

High-Performance Ambient-Condition-Processed Polymer Solar Cells and Organic Thin-Film Transistors.

Large-scale commercial synthesis of bulk-heterojunction (BHJ) solar cell materials is very challenging and both time and energy consuming. Synthesis of π-conjugated polymers (CPs) with uniform batch-to-batch molecular weight and low dispersity is a key requirement for better reproducibility of high-efficiency polymer solar cells. Herein, a conjugated polymer (CP) PTB7-Th, well known for its high performance, has been synthesized with high molecular weight and low dispersity in a closed microwave reactor. The microwave reaction procedure is known to be more controlled and consumes less energy. The precursors were strategically reacted for different reaction time durations to obtain the optimum molecular weight. All different CPs were well characterized using 1H NMR, gel permeation chromatography (GPC), UV-vis, photoluminescence (PL), electron spin resonance (ESR), and Raman spectroscopy, whereas the film morphology was extensively studied via atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXRD) techniques. The effect of molecular weight on a conventional BHJ solar cell with PC71BM acceptor was investigated to derive systematic structure-property relationships. The CP obtained after 35 min of reaction time and integrated into BHJ devices under ambient conditions provided the best performance with a power conversion efficiency (PCE) of 8.09%, which was quite similar to the results of CPs synthesized via a thermal route. An enhanced PCE of 8.47% was obtained for the optimized polymer (35 min microwave reaction product) when device fabrication was carried out inside a glovebox. The organic thin-film transistor (OTFT) device with the microwave-synthesized CP displayed better hole mobility (0.137 cm2 V-1 s-1) as compared to that with the thermally synthesized CP. This study also proved that the device stability and reproducibility of the microwave-synthesized CP were much better and more consistent than those of the thermally developed CP.