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Chemically synthesized Ag-doped SnS films for PV applications
Gedi, Sreedevi,Minnam Reddy, Vasudeva Reddy,Reddy Kotte, Tulasi Ramakrishna,Kim, Soo-Hyun,Jeon, Chan-Wook Elsevier 2016 CERAMICS INTERNATIONAL Vol.42 No.16
<P><B>Abstract</B></P> <P>The present paper reports chemically synthesized silver (Ag)-doped SnS absorbers (0–15at%) with tunable opto-electrical properties. The deposide films exhibited a polycrystalline nature and the crystallinity was improved with Ag-doping concentration upto 9at%. The optical band gap of the films was varied in the range, 1.31–1.26eV. The electrical resistivity of the films decreased significantly and the carrier concentration was improved by the Ag-doping concentration. Therefore, the SnS films grown with a 9at% Ag-doping concentration exhibited a very low electrical resistivity of 6Ω-cm and a carrier concentration of 1.2×10<SUP>16</SUP> cm<SUP>−3</SUP> with an optical energy band gap of 1.26eV due to the interstitial inclusion of Ag-atoms, which are suitable for the fabrication of eco-friendly, low cost, reliable, and highly efficient thin film solar cells.</P>
Influence of deposition temperature on the efficiency of SnS solar cells
Gedi, Sreedevi,Minnam Reddy, Vasudeva Reddy,Alhammadi, Salh,Reddy Guddeti, Phaneendra,Kotte, Tulasi Ramakrishna Reddy,Park, Chinho,Kim, Woo Kyoung Elsevier Science B.V., Amsterdam. 2019 SOLAR ENERGY -PHOENIX ARIZONA THEN NEW YORK- Vol.184 No.-
<P><B>Abstract</B></P> <P>In this paper, studies on the photovoltaic performance of the orthorhombic SnS device with respect to bath temperature are reported. Firstly, the effect of bath temperature on the physical properties of SnS layers was analyzed using appropriate characterization techniques. The deposited films exhibited an orthorhombic crystal structure with an intense (1 1 1) reflection of SnS. The band gap of 1.3 eV for good solar radiation absorption and a minimum value of electrical resistivity of 38 Ω-cm for easy carrier transport were obtained at 70 °C. In addition, the films had compact morphology with uniformly distributed large grains of approximately 220 nm. Finally, the optimal SnS absorber exhibited a high efficiency of 0.94%. This work gives a new insight into the efficient deposition of SnS solar absorbers with low material wastage and low environmental pollution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SnS films prepared by cost effective technique CBD. </LI> <LI> Bath temperature was optimized for PV absorber. </LI> <LI> Single phase orthorhombic SnS films with good morphology were prepared. </LI> <LI> SnS solar cell showed a conversion efficiency of 0.94%. </LI> <LI> The efficiency of present device is higher than reported CBD SnS (Orthorhombic)-devices. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Gedi, Sreedevi,Minnam Reddy, Vasudeva Reddy,Kotte, Tulasi Ramakrishna Reddy,Park, Youngsang,Kim, Woo Kyoung Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.465 No.-
<P><B>Abstract</B></P> <P>SnS thin films were prepared by chemical bath deposition using an environmentally friendly and economic complexing agent, tartaric acid (C<SUB>4</SUB>H<SUB>6</SUB>O<SUB>6</SUB>) with different concentrations. X-ray diffraction analysis confirmed that all the deposited films exhibited polycrystalline nature with a predominant plane of (1 1 1) related to an orthorhombic structure. The intensity of the (1 1 1) plane increased with increasing concentration of the complexing agent. Raman spectra of the films showed the characteristic vibrational modes at 94, 160, 191, and 217 cm<SUP>−1</SUP>, corresponding to orthorhombic SnS. SEM micrographs showed homogeneous surfaces with the presence of nut-shaped grains. The optical absorption coefficient for the prepared films was >10<SUP>4</SUP> cm<SUP>−1</SUP>, representing that the deposited films showed high absorption. Electrical studies revealed the p-type conducting nature of the deposited films. The SnS solar cell fabricated with a tartaric acid concentration of 1.2 M showed the highest efficiency of 1.62% with an open-circuit voltage of 0.283 V, a short-circuit current density of 13.9 mA cm<SUP>−2</SUP>, and a fill factor of 41.1%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A low-cost SnS-based solar cell is developed using chemical bath deposition. </LI> <LI> Eco-friendly tartaric acid is used as complexing agent. </LI> <LI> Single phase and good crystalline SnS absorber was prepared. </LI> <LI> SnS-based thin film solar cell showed a conversion efficiency of 1.62%. </LI> <LI> The obtained efficiency is higher than reported chemical bath deposited SnS devices. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Current density-voltage (J–V) characteristics of SnS (0.6–1.6 M)-based thin film solar cell.</P> <P>[DISPLAY OMISSION]</P>
Studies on chemical bath deposited SnS<sub>2</sub> films for Cd-free thin film solar cells
Gedi, Sreedevi,Minnam Reddy, Vasudeva Reddy,Pejjai, Babu,Park, Chinho,Jeon, Chan-Wook,Kotte, Tulasi Ramakrishna Reddy Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.4
<P><B>Abstract</B></P> <P>Tin disulfide (SnS<SUB>2</SUB>) is a simple binary metal chalcogenide and it has been proposed as a promising buffer material for Cd-free thin film solar cells. The present work explores the deposition of SnS<SUB>2</SUB> films by a facile chemical bath deposition at different deposition times in the range of 30–120min. The effect of deposition time on the structural, optical and electrical properties was investigated. The as-grown SnS<SUB>2</SUB> films showed a hexagonal crystal structure with a high intensity (001) peak at 15.03°. The films showed shuttle shaped grains that were uniformly distributed across the surface of the substrate. The films showed an optical energy band gap in the range of 2.95–2.80eV. PL spectra showed a strong emission peak in the wavelength range, 410–460nm with the variation of deposition time. The SnS<SUB>2</SUB> films prepared at a deposition time of 90min showed good crystallinity and morphology with low resistivity of 11.2Ω-cm. A solar cell with device structure of Mo/SnS/SnS<SUB>2</SUB>/i-ZnO/Al: ZnO/Ni/Ag was fabricated. The fabricated solar cell showed an efficiency of 0.91%, which validate the photovoltaic performance of SnS<SUB>2</SUB> films.</P>
Impact of high temperature and short period annealing on SnS films deposited by E-beam evaporation
Gedi, Sreedevi,Reddy, Vasudeva Reddy Minnam,Kang, Jeong-yoon,Jeon, Chan-Wook Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.402 No.-
<P><B>Abstract</B></P> <P>Thin films of SnS were deposited on Mo-substrate using electron beam evaporation at room temperature. As-deposited SnS films were annealed at a constant high temperaure of 860K for different short period of times, 1min, 3min, and 5min. The impact of heat treatment period on the physical properties of SnS films was investigated using appropriate characterization tools. XRD analysis revealed that the films were highly oriented along (111) plane with orthorhombic crystal structure. Surface morphology of as-deposited SnS films showed an identical leaf texture where as the annealed films showed large orthorombic slab shape grains in adidition to the leaf shape grains, which indicates the significance of short period annealing at high temperature. The transmission electron microscopy confirmed that those large orthorombic slabs had single-crystalline nature. The results emphasized that the short period annealing treatment at high temperature stimulated the growth of film towards the single crystallinity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Preparation SnS films using electron beam evaporation at room temperature. </LI> <LI> SnS films were annealed at a high temperaure for different short period of times. </LI> <LI> The films showed highly oriented (111) planes with orthorhombic crystal structure. </LI> <LI> Surface morphology showed bigger and faceted grains embedded in orthorombic. </LI> <LI> The TEM confirmed that big orthorombic slabs had single-crystalline nature. </LI> </UL> </P>