Interfacial charge transfer in ZnTe/ZnO nano arrayed heterostructures and their improved photoelectronic properties

Ilanchezhiyan, P.,Mohan Kumar, G.,Xiao, Fu,Madhankumar, A.,Siva, C.,Yuldashev, Shavkat U.,Cho, H.D.,Kang, T.W. North-Holland 2018 Solar Energy Materials and Solar Cells Vol. No.

<P><B>Abstract</B></P> <P>The demand for low-cost high efficient photoelectronic devices tends to drive the present need for investigations on advanced multi-functional semiconducting nanostructures. In this regard, the physico-chemical traits of sonochemically processed ZnTe nanostructures and hydrothermally grown ZnO nanostructures were studied using Raman, UV–vis absorbance, X-ray photoelectron spectroscopy and high resolution microscopic tools. The p-n ZnTe/ZnO heterojunctions were then fabricated via spin casting a colloidal ZnTe suspension on periodically aligned ZnO nanowires and investigated for their photoelectronic functionalities. The current-voltage (I-V) characteristics revealed an obvious rectifying behaviour with the forward current and rectification ratio getting improved on lowering the threshold voltages. The series resistance of the diodes were additionally studied using the dV/dlnI derivate plots. The stability of the diodes were also affirmed using their time-dependent photoresponse characteristics, which actually suggested the improved and effective separation of photo generated electron hole pairs across the interface. Finally, the ZnTe/ZnO heterojunction behaviour was assimilated using the electrochemical impedance spectroscopic (EIS) results that were studied individually for ZnTe and ZnO nanostructures and collectively across ZnTe/ZnO heterostructure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnTe integrated ZnO nanowire diodes revealed excellent rectifying behaviour/rectification ratio. </LI> <LI> Series resistance of diodes were studied using dV/dlnI derivate plots. </LI> <LI> Stability of devices were evidenced through their photoresponse characteristics. </LI> <LI> Electrochemical data revealed improved interfacial charge transfer along the heterostructure. </LI> </UL> </P>

Photoswitching and photocatalytic functions of Sn_xCu_1−xS nanostructures

Ilanchezhiyan, P.,Kumar, G. Mohan,Siva, C.,Venkatasubbu, G. Devanand,Kang, T.W.,Kim, D.Y. Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.489 No.-

<P><B>Abstract</B></P> <P>Ultra-thin semiconducting nanostructures are garnering strategic importance in energy and environment remediation applications. In this regard, Sn<SUB>x</SUB>Cu<SUB>1−x</SUB>S nanostructures were processed through an eco-friendly chemical route and investigated in detail for photoswitching and photocatalytic functions. X-ray diffraction, FT-IR, Raman, UV–vis absorbance and high-resolution microscopic tools were initially used to examine the physico-chemical traits of Sn<SUB>x</SUB>Cu<SUB>1−x</SUB>S nanostructures. Ambiguous evidence for the substitution of Sn ions in place of Cu ions was attained through X-ray photoelectron spectroscopy. The photocatalytic performance of Sn<SUB>x</SUB>Cu<SUB>1−x</SUB>S systems was investigated through effective remediation of organic dye molecules under visible light. Scavenger based photocatalytic experiments were additionally carried out to infer the degradation mechanism. Type II <I>p-n</I> Sn<SUB>x</SUB>Cu<SUB>1−x</SUB>S/In<SUB>2</SUB>S<SUB>3</SUB> heterojunction diodes were also demonstrated for the first time with improved electrical conductivity and photoelectrical performances. The rectification ratio, forward current values and photo switching capabilities of these diodes were noted to improve in the Current vs. Voltage (I-V) and Current vs. Time (I-T) curves as a function of Sn composition and applied bias potential. The excellent photo switching stability augments the photo generated carriers to be effectively separated along the p-n junctions. The enhanced photoelectronic and photocatalytic functionalities in Sn<SUB>x</SUB>Cu<SUB>1−x</SUB>S has finally been reasoned to the improved charge transfer kinetics in the respective architectures, resulting from the effective Sn interaction in hexagonal host lattice.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sn<SUB>x</SUB>Cu<SUB>1−x</SUB>S nanostructures were fabricated by hydrothermal route. </LI> <LI> The nanostructures exhibited excellent photocatalytic activity under visible light. </LI> <LI> Sn interaction in hexagonal host lattice promoted their photocatalytic performance. </LI> <LI> p-Sn<SUB>x</SUB>Cu<SUB>1−x</SUB>S/n-In<SUB>2</SUB>S<SUB>3</SUB> diodes demonstrated improved photoswitching performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Ultrasonic-assisted synthesis of ZnTe nanostructures and their structural, electrochemical and photoelectrical properties

Ilanchezhiyan, P.,Mohan Kumar, G.,Xiao, Fu,Poongothai, S.,Madhan Kumar, A.,Siva, C.,Yuldashev, Sh.U.,Lee, D.J.,Kwon, Y.H.,Kang, T.W. Elsevier 2017 Ultrasonics sonochemistry Vol.39 No.-

<P><B>Abstract</B></P> <P>Colloidal zinc telluride (ZnTe) nanostructures were successfully processed through a simple and facile ultrasonic (sonochemical) treatment for photoelectronic applications. The particle-like morphological features, phase and nature of valence state of various metal ions existing in ZnTe were examined using electron and X-ray photoelectron spectroscopic tools. Raman spectroscopic measurements revealed the dominance of exciton-phonon coupling and occurrence of TeO<SUB>2</SUB> traces in ZnTe through the corresponding vibrations. Optical bandgap of the ZnTe suspension was estimated to be around 2.15eV, authenticating the direct allowed transitions. The <I>p</I>-type electrical conductivity and charge carrier density of ZnTe were additionally estimated from the Bode, Nyquist and Mott-Schottky type impedance plots. The photoelectrical properties of ZnTe were investigated by fabricating <I>p</I>-ZnTe/<I>n</I>-Si heterostructures and studying their corresponding current-voltage characteristics under dark and white light illumination. The diodes revealed excellent rectifying behaviour with significant increase in reverse current under illumination. The stability of the devices were also affirmed through the time-dependent photoresponse characteristics, which actually suggested the improved and effective separation of photo generated electron hole pairs across the integrated heterojunctions. The obtained results also augment the potential of sonochemically processed ZnTe for application in photo detection and sensor related functions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nanostructured ZnTe were ultrasonically processed for photoelectronics. </LI> <LI> Raman, XPS and electron microscopic tools affirmed their physico-chemical traits. </LI> <LI> Electrical properties were studied using Nyquist and Mott-Schottky plots. </LI> <LI> <I>I</I>-<I>V</I> studies augment the improved photo response in p-ZnTe/n-Si heterojunctions. </LI> </UL> </P>

Excess Volumes, Speeds of Sound, Isentropic Compressibilities and Viscosities of Binary Mixtures of N-Ethyl Aniline with Some Aromatic Ketones at 303.15 K

M. Gowrisankar,S. Sivarambabu,P. Venkateswarlu,K. Siva Kumar 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.5

Densities (ρ), Viscosities (η) and ultrasonic speeds (u) of pure acetophenone (AP), propiophenone (PP), p-methyl acetophenone (p-MeAP), p-chloroacetophenone (p-ClAP) and those of their binary mixtures with N-ethyl aniline (N-EA) as a common component, were measured at 303.15 K over the entire composition range. These experimental data were used to calculate the excess volume VE, deviation in ultrasonic speeds Δu, isentropic compressibility Ks, intermolecular free length Lf, acoustic impedance Z, deviations in isentropic compressibility ΔKs, deviation in viscosity Δη and excess Gibbs free energy of activation of viscous flow (G*E) at all mole fractions of N-ethyl aniline. These parameters, especially excess functions, are found to be quite sensitive towards the intermolecular interactions between component molecules. Theoretical values of viscosity of the binary mixtures were calculated using different empirical relations and theories. The relative merits of these relations and theories were discussed. The experimental results were correlated by using the polynomial proposed by Redlich-Kister equation.

Evidencing enhanced charge-transfer with superior photocatalytic degradation and photoelectrochemical water splitting in Mg modified few-layered SnS₂

Mohan Kumar, G.,Cho, H.D.,Ilanchezhiyan, P.,Siva, C.,Ganesh, V.,Yuldashev, Sh.,Madhan Kumar, A.,Kang, T.W. Elsevier 2019 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.540 No.-

<P><B>Abstract</B></P> <P>Recently there has been immense interest in the exploration of richly available two-dimensional non-toxic layered material such as tin disulfide (SnS<SUB>2</SUB>) for potential employment in energy and environmental needs. In this regard, we report on the synthesis of few-layered Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB> nanosheets through a facile one-step hydrothermal route to address all such functions concerning photocatalysis and photoelectrochemical conversion. The crystalline order and structure of processed layered Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB> were initially found to exhibit a strong influence on their physicochemical properties. Their optical properties attest the Mg doping in SnS<SUB>2</SUB> to benefit us with enhanced visible-light absorption via red-shift in their absorption edge. In the photoluminescence spectrum the emissions observed along visible and red region signifies the association of Mg related trap states in Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB>. Next, the photocurrent and electrochemical impedance spectroscopic results revealed the Mg doping to promote the effective charge transfer process (which was beneficial to enhance their photocatalytic activity). Consequently, the layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> made photoanodes displayed 1.7 fold higher photocurrent density under simulated solar radiation with respect to their undoped counterpart. Furthermore, the layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets exhibits enhanced visible light decomposition of organic dye while compared with pristine SnS<SUB>2</SUB> nanosheets. The value of rate constants obtained for the Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets was found to be 1.4 times higher than that of pristine SnS<SUB>2</SUB>. Finally, the results obtained through the present study projects the huge potential of layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets for future multifunctional applications.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Surface induced charge transfer in Cu_xIn_2-xS₃ nanostructures and their enhanced photoelectronic and photocatalytic performance

Ilanchezhiyan, P.,Mohan Kumar, G.,Xiao, Fu,Siva, C.,Yuldashev, Shavkat U.,Lee, D.J.,Jeon, H.C.,Kang, T.W. Elsevier 2019 Solar energy materials and solar cells Vol.191 No.-

<P><B>Abstract</B></P> <P>Multi-functional semiconducting nanostructures are gaining popularity for application in photoelectronics, energy storage devices and also in industrial and environmental remediation functions. In this regard, Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> nanostructures were investigated in detail for their photoelectrical and photocatalytic performance. Their physico-chemical characteristics were at first studied using X-ray diffraction, Raman, UV–vis absorbance, X-ray photoelectron spectroscopy and high resolution electron microscopic tools. Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> based flip chip Schottky diodes were demonstrated to attest their improved conductivity and enhanced photoelectrical performance. The photo switching capabilities of a type II <I>p-n</I> CdTe/Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> heterojunction was also investigated. In both the device configurations, the current-voltage (I-V) characteristics revealed the forward current and rectification ratio to improve under lower threshold voltages. The time-dependent photoresponse characteristics affirmed the stability of diodes, augmenting the improved/effective separation of photo generated electron hole pairs under illumination. Additionally, the photocatalytic performances of Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> nanostructures were inferred under visible light conditions through effective remediation of methylene blue (MB) dye molecules. The obtained results infer the Cu interaction in tetragonal lattice of Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> to promote the surface induced charge transfer mechanism in respective nanostructures, thereby enhancing their photoelectronic and photocatalytic functionalities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> multi-functional nanostructures were fabricated by hydrothermal route. </LI> <LI> Cu interaction in tetragonal lattice of Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> promotes surface induced charge transfer. </LI> <LI> Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> diodes demonstrate improved conductivity/photoelectrical performance. </LI> <LI> Reproducible photo switching was studied along <I>p-n</I> CdTe/Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> heterojunction. </LI> <LI> Cu<SUB>x</SUB>In<SUB>2-x</SUB>S<SUB>3</SUB> nanostructures exhibit excellent photocatalytic performance under visible light. </LI> </UL> </P>

A Computational Intelligence Method for Effective Diagnosis of Heart Disease using Genetic Algorithm

P. Siva Kumar,D. Anand,V. Uday Kumar,Debnath Bhattacharyya 보안공학연구지원센터 2016 International Journal of Bio-Science and Bio-Techn Vol.8 No.2

In recent years improvement of new and effective medical domain applications has vital role in research. Computational Intelligence Systems (CIS) has profound influence in the enlargement of these effective medical field applications and tools. One of the prevalent diseases that world facing is heart disease. The Computational Intelligence Systems uses input clinical data from different knowledge resources throughout the world and applies this data on different computational intelligence tools that uses sophisticated algorithms. The sophisticated algorithms plays prominent role in the construction of medical clinical analysis tools. These tools may be used as an extra aid for the clinical diagnosis of the diseases for the doctors and clinicians. In this paper a novel method for the diagnosis of heart disease has been proposed using Genetic Algorithms. In this approach an effective association rules are inferred using Genetic Algorithm approach which uses tournament selection, crossover, mutation and new proposed fitness function. The Cleaveland data set is used for the experimentation. This data set is collected from the UCI machine learning repository experimental results are prominent when compared with some of the supervised learning techniques.

Colloidal synthesis of Gd3+ doped ZrO2 based dielectrics and their structural and electrochemical property studies

Ilanchezhiyan, P.,Siva, C.,Kang, T. W.,Mohan Kumar, G. Springer Science + Business Media 2016 Journal of materials science Materials in electron Vol.27 No.6

<P>Solution processed wide band gap dielectrics have nowadays started to receive renewed interest for practical application in semiconductor electronics. In this regard, undoped and gadolinium (Gd) doped zirconia (ZrO2) nanocrystallites were colloidally processed and their potential for dielectric applications has been demonstrated. X-ray diffraction measurements revealed the effective crystallization of nanostructures and the successful substitution of Gd ions into the cubic ZrO2 matrix. The particulate-like characteristics of undoped and Gd doped ZrO2 nanostructures were examined through the electron microscopes, which hardly revealed any difference among them. The optical band gap of ZrO2 nanostructures was determined to be around 4.64-4.80 eV from the absorbance measurements. The potential of Gd doped ZrO2 nanostructures for dielectric functions were evaluated through electrochemical impedance spectroscopic measurements. The improved capacitance values estimated from the Nyquist plots suggests the potential of the investigated materials for low power and low voltage electronic applications.</P>

Excess Volumes, Speeds of Sound, Isentropic Compressibilities and Viscosities of Binary Mixtures of N-Ethyl Aniline with Some Aromatic Ketones at 303.15 K

Gowrisankar, M.,Sivarambabu, S.,Venkateswarlu, P.,Kumar, K. Siva Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.5

Densities (${\rho}$), Viscosities (${\eta}$) and ultrasonic speeds (u) of pure acetophenone (AP), propiophenone (PP), $p$-methyl acetophenone ($p$-MeAP), $p$-chloroacetophenone ($p$-ClAP) and those of their binary mixtures with $N$-ethyl aniline ($N$-EA) as a common component, were measured at 303.15 K over the entire composition range. These experimental data were used to calculate the excess volume $V^E$, deviation in ultrasonic speeds ${\Delta}u$, isentropic compressibility $K_s$, intermolecular free length $L_f$, acoustic impedance Z, deviations in isentropic compressibility ${\Delta}K_s$, deviation in viscosity ${\Delta}{\eta}$ and excess Gibbs free energy of activation of viscous flow ($G^{*E}$) at all mole fractions of $N$-ethyl aniline. These parameters, especially excess functions, are found to be quite sensitive towards the intermolecular interactions between component molecules. Theoretical values of viscosity of the binary mixtures were calculated using different empirical relations and theories. The relative merits of these relations and theories were discussed. The experimental results were correlated by using the polynomial proposed by Redlich-Kister equation.

Antipodal signed digraphs

P. Siva Kota Reddy,B. Prashanth,T. R. Vasanth Kumar 장전수학회 2011 Advanced Studies in Contemporary Mathematics Vol.21 No.4

In this paper, we define the antipodal signed digraph A(D) of a given signed digraph S = (D, σ) and offer a structural characterization of antipodal signed digraphs.Further, we characterize signed digraphs S for which S ~ A(S) and S ~ A (S) where denotes switching equivalence and A (S) and S are denotes the antipodal signed digraph and complementary signed digraph of S respectively.