Anurag Gautam

Terbium‐doped copper oxide (CuO:Tb ³⁺ ) nanorods with different Tb ³⁺ dopant concentrations (1%, 3%, and 5%) were prepared as battery‐type supercapacitor electrode materials. The electrochemical behaviors of CuO:Tb ³⁺ electrodes depend on the Tb ³⁺ concentration. The CuO:Tb ³⁺ (3%) showed the highest specific capacity of 622.64 C/g at 1 A/g, with remarkable retention capacity of 92.6% after 10 000 charge–discharge cycles at 5 A/g. Kinetic studies of CuO:Tb ³⁺ electrode reveal that energy storage mechanism is strongly diffusion‐controlled, indicating battery‐type behavior. The hybrid solid‐state supercapacitor (CuO:Tb ³⁺ (3%)//AC) delivered maximum energy density of 33.61 Wh/kg at power density of 699.8 W/kg. The excellent electrochemical properties of CuO:Tb ³⁺ nanorods are attributed to the synergetic effects of experimentally observed improved oxygen vacancies, high surface porosity, and reduced charge transfer resistance. Owing to the excellent electrochemical properties, the CuO:Tb ³⁺ (3%)//AC supercapacitor can be utilized for lighting red light‐emitting diode for real‐time applications.

DFT/TD-DFT calculations demonstrate that TCNE/TCNQ post-functionalization of β-porphyrins (PD1–PD4) enhances intramolecular charge transfer, broadens the absorption region, narrows the band gap, and yields the highest predicted PCE (∼12.8%) for PD4.

Efficient donor-acceptor (D-A) molecular scaffolds should be developed for the advancement of organic solar cells (OSCs). Density functional theory (DFT) and time-dependent density functional theory (TDDFT) studies provide an effective methodology to perform initial studies to design and investigate D-A molecular systems. Two fluorine-substituted bis-benzothiadiazoles (FBBTs) are designed and optimized using the DFT method. The results show better planarity for FBBT2, which is attributed to π-extension between the FBBT units. A series of D-A small molecules CB1-4 are designed utilizing FBBT2 to study the effect of systematically substituting carbazole donor and cyano-based acceptor groups on the optoelectronic properties of FBBT. DFT calculations are performed using the B3LYP functional. The designed D-A scaffolds exhibit systematic tuning of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), HOMO-LUMO gap (from 2.333 eV to 1.825 eV). The observed HOMO-LUMO gap follows the trend CB1 > CB2 > CB4 > CB3. The V oc (open-circuit voltage) and power conversion efficiency (PCE) for CB1-4 are presented with the PC 71 BM acceptor. The overall trend observed for the V oc follows the order CB1 < CB4 < CB2 < CB3. The PCE trend observed using the Scharber model follows the trend CB3 > CB4 > CB2 > CB1. The results show that end cap modeling of π-extended FBBT with cyano-based acceptor groups significantly improves the observed PCE and V oc .

Production of nanoparticles at industrial scale is certainly required in near future as they are getting successfully executed in different emerging technological areas. Therefore, the scalability will be the one of the most important criteria with respect to the market demands of the nanoparticles. Some of the bench top models experiments are very expensive and may not be approved for the industrial production. The two most important nanocrystals fabrications process in the colloidal phase can be divided to two categories are heat-up and hot-injection method which is successfully used to produce the nanocrystals at the laboratory scale in very economical way. Additionally, both the process is capable of producing nanoparticles with good control on their shape and size. However, these methods have some limitations with respect to the precursor. This review will focus on nucleation and growth process in heat-up and hot-injection method and their pros and cons in scalability at industrial scale with emphasis on quantum dot, iron oxide nanoparticles and sodium lanthanum fluoride.

This article reports the systematic photoluminescence study of the various contents of gold nanocomposites in polyvinyl alcohol (PVA) films. The variations in the gold content in PVA film were 0.2, 0.5, 1.0, and 1.5 wt%. All the samples were excited at two selected wavelengths; those are at 400 nm and 532 nm. On exciting the gold‐PVA nanocomposite films at 400 nm the photoluminescence was observed in the region of 430–500 nm in comparison to pure PVA films that show an emission at 400 nm. However, on exciting the gold‐PVA nanocomposites at 532 nm, the emission was observed at 560–650 nm with a long tail till 700 nm that is unlike the pure PVA films that do not show any emission peak in this region. This suggests that emission between 430 and 500 nm regions is due to the coordination of PVA with gold nanoparticles because PVA has an emission at 400 nm. However, the emission peak between 560 and 650 nm is entirely due to the gold nanocomposite particle. The peak also shows a smaller red‐shift that is usually with the increasing nanoparticles size with the increasing content in the PVA films. The formation of gold nanoparticles was justified by X‐ray diffraction (XRD) analysis which is further supported by X‐ray photoelectron spectroscopy (XPS) analysis.

Solar cells based on p-conjugated donor-acceptor (D-A) organic molecular systems are a promising alternative to conventional electrical energy generation. D-A molecular systems, which have a triphenylamine (TPA) moiety linked with a benzothiadiazole (BTD) moiety, open the potential development of new small molecule donors for bulk heterojunction (BHJ) solar cells. Here, a series of donor-acceptor-π-acceptor (D-A-π-A) small molecule donors (SMD) derived from triphenylamine (TPA) donor and benzothiadiazole (BTD) acceptor building blocks, were designed for BHJ organic solar cells. The small molecule donors SMD1-4 were studied using density functional theory (DFT) and time dependent-DFT (TDDFT) methods, to understand the effect of cyano and fluorine group functionalization on their properties. The effect of structure alteration by cyano and fluorine group functionalization on the optoelectronic properties, the calculated highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) and the HOMO-LUMO gaps were theoretically explored. The V oc (open-circuit photovoltage) and fill factor (FF) for SMD1-4 were obtained with a PC 71 BM acceptor, which showed that these organic small molecules are potential small molecule donors for organic bulk heterojunction solar cells.

Noble metal NPs are highly attractive candidates because of their unique combination of physical, chemical, mechanical, and structural properties. A lot of developments in this area are still fascinating the materials research community, and are broadly categorized in various sectors such as chemical sensors, biosensors, Förster resonance energy transfer (FRET), and microelectronic applications. The related function and properties of the noble metals in these areas can be further tailored by tuning their chemical, optical, and electronic properties that are influenced by their size, shape, and distribution. The most widely used Au and Ag NPs in dispersed phase below 100 nm exhibit strong color change in the visible range which alters upon aggregation of the NPs. The chemical sensing of the analyte is influenced by these NPs aggregates. In this article, we have summarized the uniqueness of noble metal NPs, their synthesis methods, nucleation and growth process, and their important applications in chemical sensing, microelectronic packaging, and Förster resonance energy transfer.