Pulsed Electrochemical Deposition of CuInSe2 and Cu(In,Ga)Se2 Semiconductor Thin Films

CuInSe2 (CIS) and Cu(In,Ga)Se2 (CIGS) semiconductors are the most studied absorber materials for thin films solar cells due to their direct bandgap and large absorption coefficient. The highly efficient CIGS devices are often fabricated using expensive vacuum based technologies; however, recently electrodeposition has been demonstrated to produce CIGS devices with high efficiencies and it is easily amenable for large area films of high quality with effective material use and high deposition rate. In this context, this chapter discusses the recent developments in CIS and CIGS technologies using electrodeposition. In addition, the fundamental features of electrodeposition such as direct current, pulse and pulse-reverse plating and their application in the fabrication of CIS and CIGS films are discussed. In conclusion, the chapter summarizes the utilization of pulse electrodeposition for fabrication of CIS and CIGS films while making a recommendation for exploring the group’s unique pulse electroplating method

Cu(In,Ga)Se2 Films with Branched Nanorod Architectures Fabricated by Economic and Environmentally Friendly Pulse-Reverse Electrodeposition Route

Cu(In,Ga)Se-2 (CIGS) materials are one of the most promising solar cell technologies owing to their large absorption coefficient and tunable direct bandgap, and they have gained considerable commercial maturity. The study herein puts forward the preparation of nanostructured GIGS films containing branched nanorod architectures, which is reported for the first time. The process employs an economic pulse-reverse electrodeposition technique by utilizing the fundamentals of electro-reduction and oxidation to fabricate nanostructured GIGS and completely avoids conventional energy-intensive high-temperature annealing/selenization step. Comprehensive characterization of nanoarchitectured films reveals the stoichiometric composition and chalcopyrite structure with dominant (112) orientation. Nanostructured CIGS exhibits excellent photoactivity with a photocurrent density of 4.31 mA/cm(2) at -0.13 V vs RHE in a liquid junction, which is highest for a bare CIGS film and is attributable to its inherent high interface area and better charge transport properties compared to planar films. The ability to produce such efficient nanostructures using an economic, scalable, sustainable, and eco-friendly approach can considerably reduce fabrication costs compared with existing high-temperature bulk material preparation methods

Electrochemically Exfoliated Layered Carbons as Sustainable Anode Materials for Lead Carbon Hybrid Ultracapacitor

Lead-carbon hybrid ultracapacitors (Pb−C HUC) have become apparent as a way out of the sulfation issue of lead-acid batteries, simultaneously enhancing the system‘s power density and cycle life. In this work, exfoliated graphene oxides (EGO) were synthesized by the electrochemical exfoliation method followed by chemical activation and carbonization at 600 °C (AEGO-600). The composite electrode delivered 800 F g−1 capacitance at 1 A g−1. The Pb−C HUC fabricated using AEGO-600 anode and PbO2 cathode can achieve capacitance of 325 F g−1 at 10 A g−1 and retain 71 % capacitance after 15000 charge-discharge cycles in the voltage range of 2.3–0.8 V. The highly stable capacitance was due to the formation of layered carbons in AEGO-600 that enhanced the favorable electrolyte ion assessment to maximum active sites. Owing to the facile, cost-effective synthesis approach and better charge storage behavior, the activated-exfoliated graphene oxides thus produced could be suitable candidates for future hybrid ultracapacitor systems. © 2022 Wiley-VCH GmbH

Easy and Scalable Synthesis of NiMnCo-Oxalate Electrode Material for Supercapacitors from Spent Li-Ion Batteries: Power Source for Electrochromic Devices

The rapid transformation of battery-operated electric vehicles leads to the piling up of dead batteries after use. Finding a green and efficient way to recycle these batteries containing essential metals is crucial. Hence, the present work proposes a rapid, facile, and benign synthesis of NiMnCo-oxalate from spent lithium-ion batteries that are then directly used as electrodes for supercapacitors. NiMnCo-oxalate was extracted from dead batteries using citric acid as green leachate. Microwave irradiation was employed to expedite the process of leaching. Microwave-irradiated citric acid-assisted NiMnCo-oxalate when tested for supercapacitor showed a high specific capacity of 93 mAh g-1 (560 F g-1) at 1 A g-1. The designed asymmetric supercapacitor showed good capacitance retention with an energy and power density of 36 Wh kg-1 and 118 W kg-1, respectively. Further, a polyaniline (PANI)//tungsten oxide (WO3)-based electrochromic device was powered by the asymmetric supercapacitor indicating the successful application of recycled materials for similar applications. © 2022 American Chemical Society

Process Optimization for Pulse Reverse Electrodeposition of Graphene-Reinforced Copper Nanocomposites

<p>In the present study, processing of graphene-reinforced copper nanocomposite foils with homogenous dispersion of graphene throughout the matrix, exhibiting good mechanical properties by a simple, cost-effective, and scalable pulse reverse electrodeposition technique (PRED) with special focus on the influence of graphene content in the electrolyte to tailor the properties. A systematic approach has been adopted for enhancing the properties. Distribution of graphene nanosheets in the copper metal matrix and the microstructural properties have been studied by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Interesting observations have been made from nanoindentation studies, where hardness (∼2.7 GPa) enhanced mainly with increase in graphene content (0–0.75 g/L), while maximum elastic modulus (∼139 GPa) is achieved for a graphene content of 0.5 g/L in the electrolyte. Four-point probe testing has been adopted to evaluate the electrical features. The major contribution in enhancement of properties is found to be the presence of graphene and its uniform individual dispersion and distribution as nanosheets in the copper matrix.</p

Controllable Crystallographic Texture in Copper Foils Exhibiting Enhanced Mechanical and Electrical Properties by Pulse Reverse Electrodeposition

The texture evolution in copper foils prepared by a rapid pulse reverse electrodeposition (PRED) technique using an “additive-free” electrolyte and the subsequent correlation with the mechanical and electrical properties is investigated in this study. Control over (111), (100), and (101) crystallographic textures in copper foils has been achieved by optimization of the pulse parameters and current density. A hardness as high as 2.0–2.7 GPa, while the electrical conductivity was maintained in the same range as that of bulk copper, was exhibited by these foils. A complete study of controlling the (111), (100), and (101) textures, CSL Σ3 coherent twin boundaries, grain refinement, and their effect on the mechanical and electrical properties is performed in detail by characterizing the foils with electron backscatter diffraction, X-ray diffraction, nanoindentation, and electrical resistivity measurements. The PRED technique with short and high-energy pulses allowed the (111) texture with increase in forward off-time, while the optimized current density resulted in the formation of (100) and (101) textures. The reverse/anodic pulse applied after every forward pulse aided the minimization of residual stresses with no additives in the electrolyte, the stability of texture in the foils, grain refinement, and formation of growth twins. Among the three highly textured copper foils, those with dominant (111) texture exhibited a lower electrical resistivity of ∼1.65 × 10^–6 Ω cm and better mechanical strength compared to those with (100) and (101) textures