Showing papers by "Soumitra Satapathi published in 2021"

The effect of dimensionality on the charge carrier mobility of halide perovskites

Abstract: Metal halide perovskites (MHPs) have recently emerged as an ideal semiconductor for photovoltaic applications. Most of the advantageous properties of perovskites are dominated by their large charge carrier mobility (μ), which is a key parameter to gauge the photovoltaic performance and stability of MHPs. Simultaneously, the rich structural variation, form and crystallinity of perovskites underpin their carrier mobility. In this review article, we focus on the quantification of carrier mobility in perovskites with dimensional transformation and crystallinity. Furthermore, we have critically analyzed the variation in mobility values as probed by different analytical techniques. We also discuss the fundamental mobility limiting factors that hinder efficient charge transport in these materials and present the recent advancement with a special focus on the dimensionalities including reduced dimensional perovskites and single crystal systems. In addition, the present challenges and possible pathways for mobility enhancement are also discussed in detail.

Dark Self-Healing-Mediated Negative Photoconductivity of a Lead-Free Cs3Bi2Cl9 Perovskite Single Crystal.

Abstract: N.K.T. acknowledges a UGC Fellowship. S.S. acknowledges the Ministry of Electronics and Information Technology research grant DIC-1377-PHY.

Photosensitive Dielectric and Conductivity Relaxation in Lead-Free Cs3Bi2Cl9 Perovskite Single Crystals

Abstract: Photosensitive dielectric and conductivity relaxation was observed in all inorganic lead-free Cs3Bi2Cl9 perovskite single crystals. Using impedance and modulus spectroscopy in dark and with subsequ...

Lewis Base Passivation of Quasi-2D Ruddlesden–Popper Perovskite for Order of Magnitude Photoluminescence Enhancement and Improved Stability

Abstract: Quasi-two-dimensional (2D) Ruddlesden–Popper (RP) perovskites are currently considered as the material of choice for the next-generation light-emitting diodes (LEDs) due to their superior optoelect

Cation-Dependent Hot Carrier Cooling in the Lead-Free Bismuth Halide A3Bi2I9 (A = FA, MA, and Cs) Perovskite

Abstract: Lead-free halide perovskites, as environment-friendly materials, have received critical interest in photovoltaic applications. In this regard, the bismuth halide perovskites demonstrate better stab...

Observation of Negative Photoconductivity in Lead-Free Cs3Bi2Br9Perovskite Single Crystal

Abstract: S.S. acknowledges the ISRO Research Grant (STC-1563-PHY). N.K.T. is thankful for the UGC fellowship.

Bandgap Engineering in a Staggered-Type Oxide Perovskite Heterojunction for Efficient Visible Light-Driven Photocatalytic Dye Degradation.

Abstract: Oxide perovskite materials with ABO3 structure have been widely employed for photocatalytic applications. However, owing to the disadvantageous electron-hole recombination process and wide bandgap of some materials, the photocatalytic performance is seemingly restricted. Coupling two catalysts together through the formation of a heterojunction ensures effective charge carrier separation. The intimate interaction between the materials is propitiously useful for charge transfer, thereby increasing the efficacy. In this study, the photocatalytic activity of a KxNa(1-x)NbO3-BaBiO3 (KNN-BBO) heterojunction material for the degradation of Rhodamine 6G organic dye was investigated. The materials were extensively characterized by X-ray diffraction, UV-Vis diffused reflectance spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and N2 adsorption isotherms. The degradation efficiency of the organic contaminant under 1 sun simulated sunlight is monitored by spectral analysis from UV-Vis absorption spectroscopy. The resistance to charge transfer was also observed by electrochemical impedance spectroscopy. The effect of the sintering temperature on the photoinduced degradation activity was also included in our study. An unsintered KNN-BBO (UKB) composite material is found to be the most efficient catalyst with 84% removal efficiency as compared to the sintered one (SKB). This is attributed to the reduced bandgap with staggered-type band alignment, increased surface area, and surface oxygen vacancy states. Together with the crucial findings of this work, a probable mechanism for enhanced photocatalytic activity has been proposed here.

Effect of sulfur-doped graphene quantum dots incorporation on morphological, optical and electron transport properties of CH3NH3PbBr3 perovskite thin films

Abstract: Organic–inorganic hybrid perovskite materials have recently attracted extensive interest to develop next-generation high efficiency optoelectronic devices. However, in many of these devices, perovskite thin films are the key source of photogenerated electron and hole pairs. Therefore, a strategy for the preparation of high-quality perovskite thin films with a fewer number of traps at surfaces and grain boundaries is highly desired. In this work, sulfur-doped graphene quantum dots (S-GQDs) were synthesized and incorporated in the CH3NH3PbBr3 perovskite precursor to prepare S-GQDs incorporated perovskite thin films. The as-prepared thin films were systematically characterized using X-ray diffractometer, field emission scanning electron microscope, UV–Vis and fluorescence spectrophotometer to investigate the effect of different amounts of S-GQDs on their morphology, optical absorbance and electron transfer properties. The experimental findings revealed that multiple surface functional groups, quantum confinement and desirable electronic conductivity in S-GQDs help passivate the perovskite surface by reducing the surface and grain boundary traps. Interestingly, the incorporation of S-GQDs increased the light absorption of CH3NH3PbBr3 along with faster electron transfer across their interfaces. Hence, this strategy of S-GQDs incorporation presents a versatile and novel way to prepare highly efficient perovskite thin films for developing next-generation solar cells, light emitting diodes and other optoelectronic devices.

Recent advances, challenges, and prospects of piezoelectric materials for self-charging supercapacitor

Abstract: Numerous important advancements toward developing a novel era of supercapacitors are being published in the past few years. There has been advancement in comprehending theory, synthesizing material, and designing devices concerning supercapacitors. The development of self-charging supercapacitors is rapidly gaining attention due to converting and storing energy in an integrated system. To address the energy shortage, studies have discovered novel techniques for integrating two devices (energy harvester and storage) to create a self-charged device (wearable/versatile electronics) suitable for various applications covering micro to macroscopic level (electric vehicles and fitness monitoring systems). We summarize state-of-the-art progress toward self-charging piezoelectric supercapacitors’ mechanism, materials, and various challenges. In this review, the central theme is a fundamental understanding of energy storage and energy harvesting mechanisms. Secondly, some emerging piezoelectric materials such as polyvinylidene difluoride (PVDF), siloxene, barium titanate (BaTiO3), potassium-sodium niobate (K0.5Na0.5NbO3), oxides, and bio-piezoelectric materials are discussed. The various challenges and future developments regarding further research in this thriving field have also been highlighted.

Effect of bromine doping on the charge transfer, ion migration and stability of the single crystalline MAPb(BrxI1−x)3 photodetector

Abstract: Organic–inorganic halide perovskites (OIHPs) have emerged as a promising semiconductor for the fabrication of efficient optoelectronic devices such as photodetectors (PDs). Among all the perovskite compositions, the mixed-halide MAPb(BrxI1−x)3 formulations have gained more attention for photodetection application thanks to their tunable optoelectronic properties and great stability. However, there is still a lack of sufficient understanding of the effect of Br doping on the stability and physical properties of MAPb(BrxI1−x)3 based PDs. In this work, we prepare a series of MAPb(BrxI1−x)3 (x = 0, 0.04, 0.08, 0.12, and 0.16) single crystals (SCs) and investigate the influence of the Br content on the crystal structure, charge transport, ion migration, and recombination phenomena. Moreover, self-powered PDs with a structure of Pt/MAPb(BrxI1−x)3 SC/Pt have been developed, and their optoelectrical properties at different wavelengths of light sources (blue, green, red, and white) have been studied. We found that all the PDs exhibit the highest photoresponse under white light indicating their potential for broad spectrum detection applications. Particularly, the MAPb(Br0.16I0.84)3 SC PD exhibits the highest responsivity of 2.41 mA W−1 at white light intensity, while the highest detectivity of 15.41 × 1010 Jones was observed for the MAPb(Br0.12I0.88)3 SC PD due to the smaller amount of trap states and suppressed ion migration, as proved by impedance spectroscopy. Finally, the photostability and one-year shelf-life stability of the corresponding PDs are demonstrated.

Fabrication of Cysteamine capped-CdSe QDs anchored graphene xerogel nanosensor for facile onsite visual detection of TNT

Abstract: Owing to the importance of explosive detection for the security of land and the environment, the exploration of new methodologies for sensing electron-deficient nitroaromatics explosives (NAEs) is urgently imperative. In this work, we firstly reported a colorimetric sensor for visual detection of 2,4,6-trinitrotoluene (TNT) based on Cysteamine capped-CdSe quantum dots (QDs) decorated graphene-chitosan xerogel (GSXS), which is shown to have high signal-to-background ratio. Meisenheimer complex formation, which is a well-known sensing mechanism, is characterized by steady state and time resolved spectroscopy supported by Density-Functional-Theory (DFT). Upon Green Fluorescent Protein (GFP) illumination, this stable Meisenheimer complex actively suppresses the attributed fluorescence of QD-GSXS and thus providing a novel path for chemical sensing applications. Under optimized conditions, the sensor displayed a wide linear range from 0.0 to 311.4 μ M with a limit of detection 9.7 μ M. The developed chemosensor showed several advantages, including good selectivity and excellent stability. The proposed approach can be utilized for the rapid and sensitive detection of NAEs in the solution phase and also for clinical application.

Physiological Relevance of Angiotensin Converting Enzyme 2 As a Metabolic Linker and Therapeutic Implication of Mesenchymal Stem Cells in COVID-19 and Hypertension.

Abstract: Severe acute respiratory syndrome corona virus − 2 (SARS-CoV-2) is a single stranded RNA virus and responsible for infecting human being. In many cases the individual may remain asymptomatic. Some recently reported studies revealed that individuals of elderly age group and with pre-existing medical conditions such as hypertension, diabetes mellitus had severe consequences, even may lead to death. However, it is not clearly delineated whether hypertension itself or associated comorbidities or antihypertensive therapy contributes to the grave prognosis of COVID-19 infections. This review is aimed to decipher the exact mechanisms involved at molecular level from existing evidence and as reported. It has been reported that SARS-CoV-2 enters into the host cell through interaction between conserved residues of viral spike protein and angiotensin converting enzyme 2 (ACE2) receptor which is highly expressed in host’s cardiac and pulmonary cells and finally transmembrane protease, serine-2 (TMPRSS2), helps in priming of the surface protein. Subsequently, symptom related to multi organ involvement is primarily contributed by cytokine storm. Although various clinical trials are being conducted on renin- angiotensin- system inhibitor, till to date there is no standard treatment protocol approved for critically ill COVID-19 positive cases with pre-existing hypertension. Recently, several studies are carried out to document the safety and efficacy outcome of mesenchymal stem cell transplantation based on its immunomodulatory and regenerative properties. Therefore, identification of future novel therapeutics in the form of mesenchymal stem cell either alone or in combination with pharmacological approach could be recommended for combating SARS-CoV-2 which might be dreadful to debilitating elderly people.

Screening of potential double perovskite materials for photovoltaic applications using agglomerative hierarchical clustering.

Abstract: Data-driven approaches to solve problems in materials science have gained immense popularity in recent times due to their ability to predict unknown material properties and uncover relationships between structure and property. Machine learning algorithms like GBRT, random forest and neural networks have had tremendous success in predicting target properties of materials and design of structures for various applications. However, a major drawback for achieving results within the required accuracy using these algorithms has been the need for large datasets which can be challenging for problems when data is not sufficiently available for training the models. In this work, we propose the use of a hierarchical clustering algorithm which can work considerably better on materials science problems with small dataset constraints. We apply the algorithm to screen out promising double perovskite materials as candidates for solar cells.