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Cu2S nanocrystals incorporated highly efficient non-fullerene ternary organic solar cells
No full textHere, we report Cu2S nanocrystals based non-fullerene ternary polymer solar cells by incorporating Cu2S in conjugated polymer (PBDB-T: poly [(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5 (1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl) benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))]) and small molecule non-fullerene compound (ITIC:3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3' d']-s-indaceno[1,2-b:5,6-b]dithiophene). The devices were fabricated in inverted configuration i.e. ITO/ZnO/PBDB-T: Cu2S NCs: ITIC/MoO3/Ag. Effect of concentration of Cu2S nanocrystals on the performance parameters of PBDB-T: ITIC based organic solar cells is studied. An enhancement in the power conversion efficiency from 8.24% to 9.53% is achieved for the optimum concentration of Cu2S nanocrystals in the organic photoactive blend. The cause of improvement in the performance parameters of the device is investigated by means of the light intensity dependent electrochemical impedance spectroscopy and atomic force microscopy. It is found that the devices with Cu2S nanocrystals have less trap-assisted recombination
Dielectric and energy storage behavior of CaCu3Ti4O12 nanoparticles for capacitor application
No full textNanoparticles of CaCu3Ti4O12 (CCTO) has been synthesized by using sol- gel method. The X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) have respectively been used to confirm phase purity and determination of CCTO nanoparticles. The size of most of CCTO particles is lying in the range 50-60 nm. The dielectric constant and tangent loss of CCTO at 1 kHz has been found to be similar to 7790 and similar to 0.096 respectively. The breakdown electric field and nonlinear coefficient are found as similar to 4400 V/cm and similar to 6.3 respectively. High value of breakdown electric field and dielectric constant are respectively attributed to: (i) formation of large number of energy bands in grain boundary that traps the electrons at grain/grain boundary interface and, (ii) grain boundary inter barrier layer capacitance (IBLC). High dielectric constant and high breakdown electric field materials are very good for the pulsed power application. Discharge energy density and discharging time are obtained as similar to 7 J/cc and similar to 0.34 ms respectively. Therefore, CCTO exhibits high dielectric constant and high breakdown electric field along with very good capacitive behavior
Double perovskite Ba2CaIrO6: A Slater-type antiferromagnet system
No full textA systematic study, using first-principles methods, is performed to understand the nature and origin of electronic gap and magnetism in the double perovskite antiferromagnetic insulator Ba2CaIrO6. By virtue of its perfectly aligned IrO6, motifs the system may be anticipated as an ideal spin-orbit driven J(eff) system. However, different from the Ir+4 and Ir+5 iridates, our calculations reveal that the electronic gap in Ba2CaIrO6 is implicitly associated with an unconventional antiferromagnetic ordering of Ir spins, thereby classifying this Ir+6 iridate as a Slater-type antiferromagnetic insulator. On the other hand, spin-orbit coupling enhances the Ir 5d - O2p orbital hybridization, due to which both the magnitude of the electronic gap and the local Ir magnetic moment decreases in comparison to the scalar relativistic calculations. Our results not only affirm the validity of local approximations to the exchange-correlation potential in the scalar relativistic Kohn-Sham Hamiltonian, but also strongly convey that the insulating nature of iridates may be intimately linked with magnetism
Effectiveness of Solvent Vapor Annealing over Thermal Annealing on the Photovoltaic Performance of Non-Fullerene Acceptor Based BHJ Solar Cells
Get PDFWe explore two small molecules containing arms of dicyano-n-hexylrhodanine and diathiafulvalene wings terminated with benzothiadiazole linker, denoted as BAF-4CN and BAF-2HDT, respectively, as small molecule non-fullerene acceptors (SMNFAs) in organic solar cells. The proposed materials are mixed with a low band gap polymer donor PTB7-Th having broad absorption in the range of 400-750 nm to form solution-processed bulk heterojunctions (BHJs). The photoluminescence (PL) measurements show that both donor and acceptor can quench each other's PL effectively, implying that not only electrons are transferred from PTB7-Th -> SMNFAs but also holes are transferred from SMNFAs -> PTB7-Th for efficient photocurrent generation. Furthermore, solvent vapor annealing (SVA) processing is shown to yield a more balanced hole and electron mobility and thus suppresses the trap-assisted recombination significantly. With this dual charge transfer enabled via fine-tuning of end-groups and SVA treatment, power conversion efficiency of approximately 10% is achieved, demonstrating the feasibility of the proposed approach
Evaluation of structural, optical and mechanical behaviour of L-argininium bis(trifluoroacetate) single crystal: An efficient organic material for second harmonic generation applications
No full textIn the present technologically advanced era, non-linear optical materials especially organic derivatives are in the limelight due to their fast response in electro-optic switches and high nonlinear efficiency. Therefore, with respect to this behaviour, single crystals of L-argininium Bis(trifluoroacetate) (here in after called LABTF) an organic material was grown by slow evaporation solution growth technique. The grown single crystal was subjected to single crystal X-Ray diffractometer to validate its chemical structure and compound formation. The titled compound crystallizes into an asymmetric entity that comprises of one divalent L-argininium cation and two monovalent trifluoroacetic anion. All the intermolecular hydrogen bonds present in the LABTF crystal structure are investigated by 3D molecular Hirshfeld surface analysis and their relative involvements are disintegrated using 2D fingerprint plots. Further, the crystalline perfection assessment was performed using high-resolution X-Ray diffractometer which divulges the absence of structural grain boundaries in the obtained crystal. Thermal transport parameters of the titled compound were measured through Photoacoustic spectroscopy. The shock strength above which the crystal induces damage was found by the shock damage threshold technique. In addition, mechanical property related parameters such as hardness, stiffness and Young's Modulus were evaluated using the nanoindentation technique. These mechanical parameters resolve the reliability of devices and it can be enhanced by improving the crystal quality
Extensive study of newly developed highly dense transparent PbO-WO3-BaO-Na2O-B2O3 glasses for radiation shielding applications
No full textAmorphous PbO - WO3 - BaO - Na2O - B2O3 glass system have fabricated using traditional melt quenching method. The XRD and FTIR spectra confirm the amorphous nature and the various structural properties of the glasses respectively. The various optical properties have been measured in the spectral range 400-4000 cm(-1). Also, to understand the shielding ability of the fabricated glasses, we used the Geant4 model of a HPGe detector and WinXcom program to calculate the mass attenuation coefficient (MAC) at six energies between 356 and 2510 keV. In order to confirm the agreement between both methods, we used correlation theory and calculated the correlation coefficients (R-2) for each sample. It is found that the R-2 values are close to 1 for all samples. The MAC values at 356 keV for the prepared samples lies between 0.221 and 0.246 cm(2)/g. It is found that the usage of different concentration of PbO (from 50 to 70 mol%) affects the MAC values and thus the attenuation ability of the samples due to the heavier density of the PbO in comparison to B2O3. The effective atomic number results showed that Pb70B10 sample (contains 70 mol% of PbO) was higher than the other samples. Hence, Pb70B10 absorbs more photons than the rest of the prepared glasses
Optimization of electroless plating of gold during MACE for through etching of silicon wafer
Get PDFDeep etching of silicon (Si) is very much desirable for wide variety of applications. Under the context, a cost effective and reproducible through etching of similar to 375 mu m thick Si wafer is demonstrated through long hour metal assisted chemical etching (MACE) followed by short duration KOH etching. During MACE, apart from pH and temperature, metal catalyst size and coverage density during electroless plating plays an important role. Optimization of gold deposition in terms of plating solution concentration and deposition time during MACE is studied for effective through etching. HAuCl4 concentration of similar to 5 mM for 30 s is found to be best suited for MACE and produces deep and highly dense pores in Si with threshold pore radius similar to 250 nm and above. Following the MACE, KOH etching effectively scoops out porous Si to realize through etching
New insight into printable europium doped yttrium borate luminescent pigment for security ink application
No full textCounterfeiting has turned out to be a major area of concern these days and is becoming a serious problem worldwide. Modern technological advances have made counterfeiting of sophisticated products easy. Therefore, it is essential to search new luminescent materials to combat counterfeiting. Herein, we report that a highly luminescent YBO3:Eu3+ phosphor was synthesized by the sol-gel technique, which can be scaled up to 1 kg in a single batch at the laboratory level. This highly luminescent boron based YBO3:Eu3+ phosphor is optically active and is structurally and chemically stable. It has a particle size of similar to 110 +/- 10 nm, which provides a strong orange-red emission at 591 nm upon 245 nm excitation wavelength and is also excitable in the range of 280-480 nm excitation wavelengths. The structural/microstructural and photoluminescence (PL) behaviors were characterized by scanning electron microscopy, transmission electron microscopy/high-resolution transmission electron microscopy, and fluorescent spectroscopy. Furthermore, this phosphor was used to design luminescent security ink with a commercially available polyvinyl chloride gold medium for printing of security codes as investigated by photoluminescence (PL) mapping instruments. Thus, this facile method to synthesize a low-cost YBO3:Eu3+ phosphor based security ink offers a non-replicable security code for printing that can be easy to detect but is difficult to counterfeit. Published under license by AIP Publishin
Novel synthesis of topological insulator based nanostructures (Bi2Te3) demonstrating high performance photodetection
Get PDFThe rapid progress in 2D material research has triggered the growth of various quantum nanostructures-nanosheets, nanowires, nanoribbons, nanocrystals and the exotic nature originating through 2D heterostructures has extended the synthesis of hybrid materials beyond the conventional approaches. Here we introduce simple, one step confined thin melting approach to form nanostructures of TI (topological insulator) materials, their hybrid heterostructures with other novel 2D materials and their scalable growth. The substrate and temperature dependent growth is investigated on insulating, superconducting, metallic, semiconducting and ferromagnetic materials. The temperature dependent synthesis enables the growth of single, few quintuples to nanosheets and nanocrystals. The density of nanostructure growth is seen more on fabricated patterns or textured substrates. The fabricated nanostructure based devices show the broadband photodetection from ultraviolet to near infrared and exhibit high photoresponsivity. Ultimately, this unique synthesis process will give easy access to fabricate devices on user friendly substrates, study nanostructures and scalable growth will enable their future technology applications
A Comparative Analysis of BaTiO3/(Ba,Sr)TiO3 and BaTiO3/(Ba,Sr)TiO3/SrTiO3 Artificial Superlattices via Raman Spectroscopy
Get PDFBaTiO3/Ba50Sr50TiO3 and BaTiO3/Ba50Sr50TiO3/SrTiO3 superlattices are characterized via Raman spectroscopy. Special attention is paid to a comprehensive analysis of their polarized Raman spectra, especially, within a soft mode (E(1TO)) range. The shift of E(1TO) soft mode is found to be more pronounced for BaTiO3/Ba50Sr50TiO3/SrTiO3 sample than for BaTiO3/Ba50Sr50TiO3, presumably owing to stronger 2D compression of BT layers and abruptly increased temperature of transition from ferroelectric to paraelectric phase