Subhendu K. Panda

Pulse reverse electrodeposited NiCo2S4 nanostructures as efficient counter electrodes for dye-sensitized solar cells

Dendritic nanostructures of NiCo2S4 were deposited onto a transparent conducting glass substrate by a facile one step electrodeposition method and were used as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The NiCo2S4 thin films were deposited by both potentiostatic (PS) and pulse reverse (PR) electrodeposition techniques and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Both PS and PR techniques produced dendrite-like NiCo2S4 nanostructures. CV and EIS measurements revealed excellent electrocatalytic activities for the I−/I3− redox reaction for DSSCs. Sequential CV scanning further showed the high electrochemical stability of the NiCo2S4 dendritic nanostructures. The CEs prepared by the PR and PS techniques displayed power conversion efficiency of 7.03% and 6.01%, respectively, which are better than in the control device with thermally deposited Pt. Due to the large surface area of the NiCo2S4 dendrite structures and high electrocatalytic activity towards the reduction of I3− to I−, the electrodes demonstrated high solar cell conversion efficiency. This simple and low cost electrodeposition technique shows promise for large scale production of environmentally friendly and highly efficient NiCo2S4 CEs for DSSC applications.

Enhanced photoelectrochemical performance of CdSe quantum dot sensitized SrTiO3

We report the design and characteristics of a novel CdSe quantum dot sensitized SrTiO3 as a photoanode for photoelectrochemical water splitting with strong absorption in the UV and visible light regions up to 607 nm and an enhanced photocatalytic water splitting activity. Our results demonstrate an increase of photocurrent density with a decrease of the band gap of CdSe QDs for the sensitized SrTiO3 electrodes. Combinations of CdSe QDs of different band gaps produce a current density of up to ∼5 mA cm−2 at 0 V and ∼18 mA cm−2 at 0.75 V vs. Ag/AgCl. In comparison to the bare SrTiO3 electrode, a two-time increase in the current density is noted for the CdSe QD sensitized SrTiO3 electrodes at 0.75 V vs. Ag/AgCl. Our results demonstrate for the first time the use of SrTiO3 perovskite sensitized with tuned band gap CdSe QD heterostructures as a photoelectrocatalyst for enhanced solar water splitting.

Enhancement of Li+ Ion Conductivity in Solid Polymer Electrolytes Using Surface Tailored Porous Silica Nanofillers

The current study represents the design and synthesis of polyethylene oxide (PEO)-based solid polymer electrolytes by solvent casting approach using surface tailored porous silica as nanofillers. The surface tailoring of porous silica nanostructure is achieved through silanization chemistry using 3-glycidyloxypropyl trimethoxysilane in which silane part get anchored to the silica surface whereas epoxy group get stellated from the silica surface. Surface tailoring of silica with epoxy group increases the room temperature electrochemical performances of the resulting polymer electrolytes. Ammonical hydrolysis of organosilicate precursor is used for both silica preparation and their surface tailoring. The composite solid polymer electrolyte films are prepared by solution mixing of PEO with lithium salt in presence of silica nanofillers and cast into film by solvent drying, which are then characterized by impedance measurement for conductivity study and wide angle x-ray diffraction for change in polymer crystallinity. Room temperature impedance measurement reveals Li+ ion conductivity in the order of 10−4 S cm−1, which is correlated to the decrease in PEO crystallinity. The enhancement of conductivity is further observed to be dependent on the amount of silica as well as on their surface characteristics.

A short review on the advancements in electroplating of CuInGaSe2 thin films

Thin-film solar cell devices based on copper indium gallium diselenide (CIGSe) chalcogenide materials fabricated by vacuum-based deposition techniques have already achieved lab scale efficiency beyond 21%. For industrial-scale applications, non-vacuum deposition technique such as electrodeposition and screen printing is considered to be suitable approaches for reducing the device fabrication cost. Moreover, electrodeposition has the potential to prepare large area thin films as it requires cheap raw material sources and equipment capital. Hence, it is imperative to understand the current status and advancements in the electroplating techniques of the CIGSe thin films. This article reviews on the experimental advances in electroplating of ternary CuInSe2 and quaternary CIGSe. Various approaches in electrodeposition, influential experimental parameters, and the deposition mechanisms which are related to the final cell efficiency are discussed in detail.