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>

High performance photodiodes based on chemically processed Cu doped SnS₂ nanoflakes

Mohan Kumar, G.,Xiao, Fu,Ilanchezhiyan, P.,Yuldashev, Sh.,Madhan Kumar, A.,Cho, H.D.,Lee, D.J.,Kang, T.W. Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.455 No.-

<P><B>Abstract</B></P> <P>In this work, Cu doped SnS<SUB>2</SUB> nanoflakes were synthesized through a simple hydrothermal method. The influence of Cu doping on the structural, optical and electrical properties of SnS<SUB>2</SUB> were investigated in detail. Optical properties explores the Cu doping in SnS<SUB>2</SUB> crystal lattice to result with a red-shift in absorption spectrum, which benefits visible-light absorption. Photodiodes were further fabricated by spin coating Cu doped SnS<SUB>2</SUB> nanoflakes on p-type silicon (Si). Electrical and photoelectrical parameters of Cu doped SnS<SUB>2</SUB> nanoflakes were determined by studying their impedance and current–voltage (I–V) characteristics, respectively. The diodes were found to exhibit excellent rectifying behavior and good sensitivity on par to pristine photodiodes. Impedance results identified the resistance of device to reduce considerably on Cu doping. The enhanced photoelectrical properties of the heterojunctions has been ascribed to Cu ions, which act as effective dopant and contribute to the varied carrier concentration in SnS<SUB>2</SUB>. Finally the obtained results suggest the potential of Cu-doped SnS<SUB>2</SUB> for application in photodetection and sensors applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu doped SnS<SUB>2</SUB> nanoflakes were synthesized in hexagonal phase. </LI> <LI> Nature of charge carriers/carrier density was determined using Mott-Schottky plots. </LI> <LI> Photodiode based on Cu doped SnS<SUB>2</SUB> nanoflakes were fabricated on p-Si substrate. </LI> <LI> Photodiode revealed improved photocurrent and responsitivity values under illumination. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

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>

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>

Solution processed n-In2O3nanostructures for organic-inorganic hybrid p-n junctions

Kumar, G. Mohan,Kumar, A. Madhan,Ilanchezhiyan, P.,Kang, T. W. The Royal Society of Chemistry 2014 Nanoscale Vol.6 No.19

<P>Solution processed organic-inorganic bulk hybrid heterostructures are nowadays considered as the most promising elements to perform efficient optoelectronic functions. In this regard, In2O3 based hybrid heterostructures were fabricated using polypyrrole and their role as efficient interfacial layers was studied using polypyrrole/ZnO nanowires. The In2O3 nanostructures were synthesized through a facile wet chemical approach at an average scale of less than 10 nm in cubic phase. The presence of O and In related defects was studied through emission spectra; these were also found to exhibit their predominance in Raman measurements. The n-type characteristics and donor density value of around 1020 cm-3 were evaluated for the In2O3 specimens via Mott-Schottky plots. The role of In2O3 nanostructures as active/interfacial layers was then studied using the current-voltage characteristics obtained across the hybrid heterostructures made of polypyrrole/In2O3, polypyrrole/ZnO and polypyrrole/In2O3/ZnO. Organic-inorganic p-n diodes were obtained via in situ chemical polymerization, drop casting and hydrothermal routes. Cyclic voltammograms and Nyquist plots were used to study the reduction mechanism taking place in the nanostructures that actually results with the formation of metallic In, which plays a vital role in establishing the required conduction electrons. The same has been reasoned for the improved rectification characteristics observed across the diodes.</P>

Electrical property studies on chemically processed polypyrolle/aluminum doped ZnO based hybrid heterostructures

Mohan Kumar, G.,Ilanchezhiyan, P.,Madhan Kumar, A.,Yuldashev, Sh.U.,Kang, T.W. Elsevier 2016 Chemical physics letters Vol.649 No.-

<P>A hybrid structure based on p-type polypyrolle (PPy) and n-type aluminum (Al) doped ZnO nanorods was successfully constructed. The effect of Al doping on material properties of wurtzite structured ZnO were studied using several analytical techniques. To establish the desired hybrid structure, pyrrole monomers were polymerized on hydrothermally grown Al doped ZnO nanorods by chemical polymerization. The current-voltage characteristics on the fabricated PPy/A1 doped ZnO heterostructures were found to exhibit excellent rectifying characteristics under dark and illumination conditions. The obtained results augment the prescribed architecture to be highly suitable for high-sensitivity optoelectronic applications. (C) 2016 Elsevier B.V. All rights reserved.</P>

Improvement of characteristics of p-ZnTe and n-ZnO hetero-structured devices

Hak Dong Cho,Im Taek Yoon,P. Ilanchezhiyan,G. Mohan Kumar,Deuk Young Kim,Fu Xiao,Tae Won Kang,Sh.U. Yuldashev,Juwon Lee 한국진공학회 2019 한국진공학회 학술발표회초록집 Vol.2019 No.2

Studies on electrochemical properties of CuO-In₂O₃ based nanocomposites

Kumar, G.M.,Kumar, A.M.,Ilanchezhiyan, P.,Kang, T.W. North Holland 2015 Chemical physics letters Vol.637 No.-

CuO-In<SUB>2</SUB>O<SUB>3</SUB> based nanocomposites were synthesized through a facile wet chemical approach and their structural/morphological characteristics were investigated using X-ray diffraction and transmission electron microscopic measurements, respectively. The composites were drop cast over transparent conducting substrates (from colloidal media) at room temperature to fabricate the working electrodes for electrochemical studies. The charge transfer resistance, nature of charge carriers, flat band potential and carrier density of CuO-In<SUB>2</SUB>O<SUB>3</SUB> was determined using Nyquist and Mott-Schottky plots. The potential of solution processed CuO-In<SUB>2</SUB>O<SUB>3</SUB> nanocomposites for electronic functions was evaluated by fabricating heterojunction diodes based on p-CuO-In<SUB>2</SUB>O<SUB>3</SUB>/n-Si architectures. Their diode characteristics revealed an excellent rectifying behaviour.

Fabrication of polypyrrole/ZnO nanowires based organic–inorganic hybrid p-n junctions

Mohan Kumar, G.,Madhan Kumar, A.,Ilanchezhiyan, P.,Kang, T. W. Springer Science + Business Media 2015 Journal of materials science Materials in electron Vol.26 No.4

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>