Constrained flexibility in PNA: DNA binding studies with bridged aminopropylglycyl PNA

Introduction of methylene bridges in aegPNA and apgPNA molecules give rise to cyclic five and six membered ring structures. Synthesis of a new six membered cyclic PNA monomer, aminopipecolyl PNA (pipPNA) is reported. Incorporation of pipPNA into PNA oligomers and comparative binding with target DNA sequences is studied

Structural, electronic, and optical properties of lead-free halide double perovskite Rb2AgBiI6: a combined experimental and DFT study

Hybrid lead halide perovskites have emerged as an attractive photoactive semiconductor for optoelectronic applications such as photovoltaics. However, their toxicity and stability issues pose significant challenges to its wide-scale applications and hence the need to find alternative perovskites that are stable and environmentally benign. Recently, double perovskites have been suggested as a potential alternative owing to their non-toxicity and high stability. In the present study, we report the first synthesis of Rb2AgBiI6 thin films in a cubic crystal structure using a facile room-temperature single-step solution process synthesis method and explore their potential optoelectronic applications. The structural, thermal, and mechanical stability, electronic, and optical properties are studied using various experimental techniques, and the results are further corroborated by first-principles density functional theory (DFT) calculations. The Rb2AgBiI6 film has an estimated band gap ∼ of 1.98 eV with the demonstrated thermal stability of ∼ 440 oC, suggesting its potential suitability for low-cost thin-film solar cells. The initial fabricated photovoltaic device without optimization of the synthesis conditions and device architecture show power conversion efficiency (PCE) of 0.1 % and an open-circuit voltage (Voc) of 0.46 V. The successful incorporation of Rb in Bi-based double perovskite should open the way to a new class of Rubidium-based perovskites with significant potential for optoelectronic applications

Electrodeposition of template free hierarchical ZnO nanorod arrays via a chloride medium

We have successfully grown template and buffer free ZnO nanorod films via chloride medium by controlling bath temperature in a simple and cost effective electrochemical deposition method. Thin films of ZnO nano-rods were obtained by applying a potential of −0.75 V by employing Ag/AgCl reference electrode for 4 h of deposition time. The CV measurements were carried out to determine potential required to deposit ZnO nanorod films whereas chronoamperometry studies were carried out to investigate current and time required to deposit ZnO nanorod films. The formation of ZnO nanorod has been confirmed by scanning electron microscopy (SEM) and Raman spectroscopy. Low angle XRD analysis confirms that ZnO nanorod films have preferred orientation along (101) direction with hexagonal wurtzite crystal structure. The SEM micrographs show nice surface morphology with uniform, dense and highly crystalline hexagonal ZnO nanorods formation. Bath temperature has a little influence on the orientation of nanorods but has a great impact on their aspect ratio. Increase in bath temperature show improvement in crystallinity, increase in diameter and uniform distribution of nanorods. Compositional analysis shows that the amount of oxygen is ~49.35 % and that of Zn is ~50.65 %. The optical band gap values were found to be 3.19 and 3.26 eV for ZnO nanorods prepared at bath temperature 70 and 80 °C respectively. These results indicate that by controlling the bath temperature band gap of ZnO nanorods can be tailored. The obtained results suggest that it is possible to synthesize ZnO nanorod films by a simple, cost effective electrodeposition process which can be useful for opto-electronic devices fabrication

Electrodeposition of template free hierarchical ZnO nanorod arrays via a chloride medium

We have successfully grown template and buffer free ZnO nanorod films via chloride medium by controlling bath temperature in a simple and cost effective electrochemical deposition method. Thin films of ZnO nano-rods were obtained by applying a potential of −0.75 V by employing Ag/AgCl reference electrode for 4 h of deposition time. The CV measurements were carried out to determine potential required to deposit ZnO nanorod films whereas chronoamperometry studies were carried out to investigate current and time required to deposit ZnO nanorod films. The formation of ZnO nanorod has been confirmed by scanning electron microscopy (SEM) and Raman spectroscopy. Low angle XRD analysis confirms that ZnO nanorod films have preferred orientation along (101) direction with hexagonal wurtzite crystal structure. The SEM micrographs show nice surface morphology with uniform, dense and highly crystalline hexagonal ZnO nanorods formation. Bath temperature has a little influence on the orientation of nanorods but has a great impact on their aspect ratio. Increase in bath temperature show improvement in crystallinity, increase in diameter and uniform distribution of nanorods. Compositional analysis shows that the amount of oxygen is ~49.35 % and that of Zn is ~50.65 %. The optical band gap values were found to be 3.19 and 3.26 eV for ZnO nanorods prepared at bath temperature 70 and 80 °C respectively. These results indicate that by controlling the bath temperature band gap of ZnO nanorods can be tailored. The obtained results suggest that it is possible to synthesize ZnO nanorod films by a simple, cost effective electrodeposition process which can be useful for opto-electronic devices fabrication

Substrate temperature dependent structural, optical, morphology and electrical properties of RF sputtered CdTe thin films for solar cell application

In this work, we have studied the influence of substrate temperature on structural, morphology optical, and electrical properties of CdTe thin films deposited by RF magnetron sputtering. Films were analyzed by using variety of techniques such as low angle X-ray Diffraction, UV–Visible spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDAX) Hall Measurement etc. Low angle XRD analysis showed that CdTe films are polycrystalline and has cubic structure with preferred orientation is along (111) direction. Raman scattering studies revealed the presence of single phase CdTe over the entire range of substrate temperature studied. The FE-SEM analysis showed that CdTe growth process occurred predominantly by grain growth and not through the layer-by-layer mode. Compositional analysis carried out using EDAX suggests that CdTe films deposited at low substrate temperatures are Te rich and that at higher temperatures is Cd rich. Electrical resistivity of CdTe films decreases with increase in substrate temperature and whereas positive increase in Hall coefficient suggests as-deposited CdTe films are p-type. The UV–Visible spectroscopy analysis showed that the band gap increases from 1.47 to 1.51 eV when the substrate temperature increased from 50 to 300 °C. Such optimum band gap CdTe can be use as absorber material in photovoltaic applications like the CdS/CdTe and ZnO/CdTe solar cells