The Experts below are selected from a list of 3345 Experts worldwide ranked by ideXlab platform
S. Moorthy Babu - One of the best experts on this subject based on the ideXlab platform.
-
Surface-treated Cu_2ZnSnS_4 nanoflakes as Pt-free inexpensive and effective counter electrode in DSSC
Journal of Materials Science: Materials in Electronics, 2020Co-Authors: C. Imla Mary, M. Senthilkumar, G. Manobalaji, S. Moorthy BabuAbstract:Inexpensive semiconducting counter electrode (CE) was fabricated from copper zinc tin Sulfide (CZTS) nanoflakes (NFs) through simple non-vacuum-based techniques. The kesterite CZTS NFs were synthesized by hot injection method using oleic acid as solvent. CZTS CE was prepared through solid-state ligand exchange method using ammonium Sulfide Salt ((NH_4)_2S) as the displacement ligand. Thin-film CZTS CE (on FTO substrate) was developed through inexpensive layer-by-layer (LbL) approach, without any post-treatment such as toxic sulfurization process. Hence, the fabrication of CZTS CE through this approach is scalable. The CZTS thin film showed NFs like morphology with higher surface area and achieved good electrocatalytic activity towards the reduction of iodide electrolyte. Two DSSCs using different CEs (CZTS NFs and Pt) were fabricated in separate cell structures in our laboratory. DSSC with CZTS NFs as CE showed the power conversion efficiency of 2.95% which is comparable to the DSSC with Pt (3.11%).
-
Surface-treated Cu_2ZnSnS_4 nanoflakes as Pt-free inexpensive and effective counter electrode in DSSC
Journal of Materials Science: Materials in Electronics, 2020Co-Authors: C. Imla Mary, M. Senthilkumar, G. Manobalaji, S. Moorthy BabuAbstract:Inexpensive semiconducting counter electrode (CE) was fabricated from copper zinc tin Sulfide (CZTS) nanoflakes (NFs) through simple non-vacuum-based techniques. The kesterite CZTS NFs were synthesized by hot injection method using oleic acid as solvent. CZTS CE was prepared through solid-state ligand exchange method using ammonium Sulfide Salt ((NH_4)_2S) as the displacement ligand. Thin-film CZTS CE (on FTO substrate) was developed through inexpensive layer-by-layer (LbL) approach, without any post-treatment such as toxic sulfurization process. Hence, the fabrication of CZTS CE through this approach is scalable. The CZTS thin film showed NFs like morphology with higher surface area and achieved good electrocatalytic activity towards the reduction of iodide electrolyte. Two DSSCs using different CEs (CZTS NFs and Pt) were fabricated in separate cell structures in our laboratory. DSSC with CZTS NFs as CE showed the power conversion efficiency of 2.95% which is comparable to the DSSC with Pt (3.11%).
Anunay Samanta - One of the best experts on this subject based on the ideXlab platform.
-
CdTe Quantum Dots in Ionic Liquid: Stability and Hole Scavenging in the Presence of a Sulfide Salt
The Journal of Physical Chemistry C, 2014Co-Authors: M. Chandra Sekhar, Kotni Santhosh, Jaini Praveen Kumar, Navendu Mondal, S. Soumya, Anunay SamantaAbstract:The light-harvesting properties of both CdSe and CdTe nanocrystals are ideally suited for their use in quantum dot (QD)-sensitized solar cells. However, corrosion of the CdTe QD in an aqueous environment in the presence of Sulfide/polySulfide electrolyte renders it unsuitable despite its better electron injection ability (compared to CdSe QD) to a large band-gap semiconductor like TiO2. In this work, we explore the stability of a CdTe QD, which we have developed exclusively for its use in ionic liquids, in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid in the presence of S2– and investigate the hole transfer process from this photoexcited QD to S2–. We not only demonstrate that an appropriate capping of the CdTe QD and use of an ionic liquid in place of the aqueous medium enhances the stability of the QD significantly in the presence of S2– but also provide evidence of hole transfer from a photoexcited QD to the Sulfide Salt using steady-state and time-resolved emission and ultrafast transie...
Pawan Tyagi - One of the best experts on this subject based on the ideXlab platform.
-
Sulfide and Fluoride Ions Based Passivation of GaAs(100) Surface and Concept of Combining Surface Passivation with Tunnel Junction Based Molecular Devices
2019Co-Authors: Pawan TyagiAbstract:Sulfur interaction with GaAs can reduce the harmful effect of surface states on recombination attributes. Apart from surface passivation, study of sulfur bonding on GaAs is also important for developing novel molecular electronics and molecular spintronics devices, where a molecular channel can be connected to at least one GaAs surface via thiol functional group. Excess thiol functional groups that are not involved in making molecular device channels can serve as the passivants to quench surface states. However, the primary challenge lies in increasing the stability and effectiveness of the sulfur passivated GaAs. We have investigated the effect of single and double step surface passivation of n-GaAs(100) by using the Sulfide and fluoride ions. Our single-step passivation involved the use of Sulfide and fluoride ions individually. However, the two kinds of double-step passivations were performed by treating the n-GaAs surface. In the first approach GaAs surface was firstly treated with Sulfide ions and secondly with fluoride ions, respectively. In the second double step approach GaAs surface was first treated with fluoride ions followed by Sulfide ions, respectively. Sulfidation was conducted using the nonaqueous solution of sodium Sulfide Salt. Whereas the passivation steps with fluoride ion was performed with the aqueous solution of ammonium fluoride. Both sulfidation and fluoridation steps were performed either by dipping the GaAs sample in the desired ionic solution or electrochemically. Photoluminescence was conducted to characterize the relative changes in surface recombination velocity due to the single and double step surface passivation. Photoluminescence study showed that the double-step chemical treatment where GaAs was first treated with fluoride ions followed by the Sulfide ions yielded the highest improvement. The time vs. photoluminescence study showed that this double-step passivation exhibited lower degradation rate as compared to widely discussed Sulfide ion passivated GaAs surface. We also conducted surface elemental analysis using Rutherford Back Scattering to decipher the near surface chemical changes due to the four passivation methodologies we adopted. The double-step passivations affected the shallower region near GaAs surface as compared to the single step passivations.
-
GaAs(100) Surface Passivation with Sulfide and Fluoride Ions
MRS Advances, 2017Co-Authors: Pawan TyagiAbstract:Interaction of GaAs with sulfur can be immensely beneficial in reducing the deleterious effect of surface states on recombination attributes. Bonding of sulfur on GaAs is also important for developing novel molecular devices and sensors, where a molecular channel can be connected to GaAs surface via thiol functional group. However, the primary challenge lies in increasing the stability and effectiveness of the sulfur passivated GaAs. We have investigated the effect of single and double step surface passivation of n-GaAs(100) by using the Sulfide and fluoride ions. Our single-step passivation involved the use of Sulfide and fluoride ions individually. However, the two kinds of double-step passivations were performed by treating the n-GaAs surface. In the first approach GaAs surface was firstly treated with Sulfide ions and secondly with fluoride ions, respectively. In the second double step approach GaAs surface was first treated with fluoride ions followed by Sulfide ions, respectively. Sulfidation was conducted using the nonaqueous solution of sodium Sulfide Salt. Whereas the passivation steps with fluoride ion was performed with the aqueous solution of ammonium fluoride. Both sulfidation and fluoridation steps were performed either by dipping the GaAs sample in the desired ionic solution or electrochemically. Photoluminescence was conducted to characterize the relative changes in surface recombination velocity due to the single and double step surface passivation. Photoluminescence study showed that the double-step chemical treatment where GaAs was first treated with fluoride ions followed by the Sulfide ions yielded the highest improvement. The time vs. photoluminescence study showed that this double-step passivation exhibited lower degradation rate as compared to widely discussed Sulfide ion passivated GaAs surface. We also conducted surface elemental analysis using Rutherford Back Scattering to decipher the near surface chemical changes due to the four passivation methodologies we adopted. The doublestep passivations affected the shallower region near GaAs surface as compared to the single step passivations.
C. Imla Mary - One of the best experts on this subject based on the ideXlab platform.
-
Surface-treated Cu_2ZnSnS_4 nanoflakes as Pt-free inexpensive and effective counter electrode in DSSC
Journal of Materials Science: Materials in Electronics, 2020Co-Authors: C. Imla Mary, M. Senthilkumar, G. Manobalaji, S. Moorthy BabuAbstract:Inexpensive semiconducting counter electrode (CE) was fabricated from copper zinc tin Sulfide (CZTS) nanoflakes (NFs) through simple non-vacuum-based techniques. The kesterite CZTS NFs were synthesized by hot injection method using oleic acid as solvent. CZTS CE was prepared through solid-state ligand exchange method using ammonium Sulfide Salt ((NH_4)_2S) as the displacement ligand. Thin-film CZTS CE (on FTO substrate) was developed through inexpensive layer-by-layer (LbL) approach, without any post-treatment such as toxic sulfurization process. Hence, the fabrication of CZTS CE through this approach is scalable. The CZTS thin film showed NFs like morphology with higher surface area and achieved good electrocatalytic activity towards the reduction of iodide electrolyte. Two DSSCs using different CEs (CZTS NFs and Pt) were fabricated in separate cell structures in our laboratory. DSSC with CZTS NFs as CE showed the power conversion efficiency of 2.95% which is comparable to the DSSC with Pt (3.11%).
-
Surface-treated Cu_2ZnSnS_4 nanoflakes as Pt-free inexpensive and effective counter electrode in DSSC
Journal of Materials Science: Materials in Electronics, 2020Co-Authors: C. Imla Mary, M. Senthilkumar, G. Manobalaji, S. Moorthy BabuAbstract:Inexpensive semiconducting counter electrode (CE) was fabricated from copper zinc tin Sulfide (CZTS) nanoflakes (NFs) through simple non-vacuum-based techniques. The kesterite CZTS NFs were synthesized by hot injection method using oleic acid as solvent. CZTS CE was prepared through solid-state ligand exchange method using ammonium Sulfide Salt ((NH_4)_2S) as the displacement ligand. Thin-film CZTS CE (on FTO substrate) was developed through inexpensive layer-by-layer (LbL) approach, without any post-treatment such as toxic sulfurization process. Hence, the fabrication of CZTS CE through this approach is scalable. The CZTS thin film showed NFs like morphology with higher surface area and achieved good electrocatalytic activity towards the reduction of iodide electrolyte. Two DSSCs using different CEs (CZTS NFs and Pt) were fabricated in separate cell structures in our laboratory. DSSC with CZTS NFs as CE showed the power conversion efficiency of 2.95% which is comparable to the DSSC with Pt (3.11%).
Prasanta Kumar Guha - One of the best experts on this subject based on the ideXlab platform.
-
Pt decorated MoS2 nanoflakes for ultrasensitive resistive humidity sensor.
Nanotechnology, 2018Co-Authors: Debasree Burman, Sumita Santra, Panchanan Pramanik, Prasanta Kumar GuhaAbstract:In this work, we report the fabrication of a low power, humidity sensor where platinum nanoparticles (NPs) decorated few-layered Molybdenum disulphide (MoS2) nanoflakes have been used as the sensing layer. A mixed solvent was used to exfoliate the nanoflakes from the bulk powder. Then the Pt/MoS2 composites were prepared by reducing Pt NPs from chloroplatinic acid hexahydrate using a novel reduction technique using Sulfide Salt. The successful reduction and composite preparation were confirmed using various material characterization tools like Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Raman spectroscopy and UV-visible spectroscopy (UV-Vis). The humidity sensors were prepared by drop-coating the Pt-decorated MoS2 on gold interdigitated electrodes and then exposed to various levels of relative humidity (RH). Composites with different weight ratios of Pt were tested and the best response was shown by the Pt/MoS2 (0.25:1) sample with a record high response of ~4000 times at 85% RH. The response and recovery times were ~92 seconds and ~154 seconds respectively with repeatable behavior. The sensor performance was found to be stable when tested over a few months. The underlying sensing mechanisms along with detailed characterization of the various composites have been discussed.
