Dr. Ajay Singh Verma
@dbuu.ac.in
Professor Department of Physics
Uttaranchal University Dehradun
EDUCATION
Ph. D., DSKPDF, MIETI FISCA
RESEARCH INTERESTS
Hybrid perovskite nanoparticles solar cell devices and other optical materials
Scopus Publications
Scopus Publications
Upasana Rani, Peeyush Kumar Kamlesh, Rashmi Singh, Tanuj Kumar, Rajeev Gupta, Samah Al-Qaisi, Kulwinder Kaur, and Ajay Singh Verma
World Scientific Pub Co Pte Ltd
Distinct types of materials are being explored for usage in thermoelectric (TE) and photovoltaic (PV) systems in order to alleviate the energy problem. In order to create nontoxic, more stable, and best-performance energy convergence devices, the state-of-the-art hybrid halide double perovskites (HHDPs) compound has been identified as a potential TE material and potential replacement for hazardous lead. We have proposed a new HHDP material (CH3NH[Formula: see text]AgInCl6 and performed its theoretical investigation via the full potential linear augmented plane wave (FP-LAPW) method. The computational results show that the studied compound exhibits a direct bandgap of 3.708[Formula: see text]eV and has exceptional PV characteristics in the ultraviolet (UV) region. The obtained thermodynamic (TD) characteristics confirm that the titled compound is thermally stable at various temperatures and pressures. At 300 K, the examined HHDP material has the highest ZT (=2.23) in the p-region. Materials with higher ZTe values are substantially more important for generating electrical energy through waste heat. The ZTe result validates the use of these materials in TE devices at ambient temperature. The parameters of this compound have been computed for the first time. This study identifies (CH3NH[Formula: see text]AgInCl6 as a novel HHDP compound. Through an in-depth exploration of its properties, this study offers valuable insight for further research with potential applications in clean energy systems.
Tarun Kumar Joshi, Giriraj Sharma, Yogita R. Sharma, and Ajay Singh Verma
Elsevier BV
Monika Rani, Peeyush Kumar Kamlesh, Sunil Kumawat, Anuradha, Upasana Rani, Gunjan Arora, and Ajay Singh Verma
Elsevier BV
Pinki Rani, Sunil Rohilla, and Ajay Singh Verma
AIP Publishing
Anusha Dubey, Naincy Pandit, Rashmi Singh, Tarun Kumar Joshi, Banwari Lal Choudhary, Peeyush Kumar Kamlesh, Samah Al-Qaisi, Tanuj Kumar, Kulwinder Kaur, and Ajay Singh Verma
Springer Science and Business Media LLC
Nishi Mehak, Bindu Rani, Aadil Fayaz Wani, Shakeel Ahmad Khandy, Ajay Singh Verma, Atif Mossad Ali, M.A. Sayed, Shobhna Dhiman, and Kulwinder Kaur
Elsevier BV
Abderrazak Boutramine, Samah Al-Qaisi, Saidi Samah, Nazia Iram, Tahani A. Alrebdi, Sonia Bouzgarrou, Ajay Singh Verma, Soufyane Belhachi, and Ramesh Sharma
Springer Science and Business Media LLC
Abderrazak Boutramine, Samah Al-Qaisi, Malak Azmat Ali, Tahani A. Alrebdi, Afaf Khadr Alqorashi, Ajay Singh Verma, Zeesham Abbas, El Sayed Yousef, Ramesh Sharma, and Muhammad Mushtaq
Springer Science and Business Media LLC
Priya Jasrotia, Bhanu Priya, Raj Kumar, Indra Sulania, Rajeev Gupta, Ajay Singh Verma, D. Kanjilal, and Tanuj Kumar
Elsevier BV
Sunita Kumari, Upasana Rani, Monika Rani, Rashmi Singh, Peeyush Kumar Kamlesh, Sarita Kumari, Tanuj Kumar, and Ajay Singh Verma
World Scientific Pub Co Pte Ltd
We have undertaken an ab initio investigation of emerging metal lead-free halide double perovskite materials for renewable energy applications using the WIEN2k simulation code. These materials have garnered significant attention from the research community due to their potential utility in electronic devices. Through an analysis of their electronic structure, we have ascertained that these materials exhibit characteristics of direct band gap semiconductors, falling within the energy range spanning 0.755 to 1.825[Formula: see text]eV. Furthermore, to check their suitability for use in photovoltaic devices, optical properties have been investigated. The thermoelectric potential of these materials has been explored using the BoltzTraP simulation code. The study of thermoelectric parameters indicates that the studied materials are effective thermoelectric materials with a strong potential for n-type doping. Additionally, thermodynamic parameters have been investigated to check their thermal stability, required to make them promising candidates for a wide range of renewable energy applications.
Samah Al‐Qaisi, Nazia Iram, Saidi Samah, Afaf Khadr Alqorashi, A. I. Aljameel, Tahani A. Alrebdi, Zeesham Abbas, S. Bouzgarrou, Md. Ferdous Rahman, and Ajay Singh Verma
Wiley
AbstractLead‐free double perovskites are unique materials for transport and optoelectronic applications that use clean resources to generate energy. Using first‐principle computations, this study thoroughly investigates the structural, thermoelectric, and optical attributes of A2TlAgF6 (A = Rb, Cs). Tolerance factor and formation energy estimates are used to verify that these materials exist in the cubic phase. Elastic constants with high melting temperature values are ductile when evaluated for mechanical stability using the Born stability criterion. The optical absorption band is adjusted from 2 to 4 eV via band gaps of 1.88 and 1.99 eV, as indicated by band structures. Analysis of optical properties reveals perfect absorption in the visible spectrum, whole polarization, and low optical loss. Furthermore, thermoelectric properties are assessed at 300, 500, and 700 K in the range of −0.5 to 3 eV for chemical potential (μ). The materials exhibit significant improvements in the Figure of Merit scale due to their elevated electrical conductivity, Seebeck coefficient, and extremely low thermal conductivity values.
Ghanshyam Lal Menaria, Upasana Rani, Peeyush Kumar Kamlesh, Rashmi Singh, Monika Rani, Nihal Singh, Dinesh C. Sharma, and Ajay Singh Verma
World Scientific Pub Co Pte Ltd
Due to their distinct characteristics and prospective uses in several disciplines, half-Heusler (HH) materials are a family of intermetallic compounds that have garnered a lot of attention. HH compounds have a cubic crystal structure and exhibit a wide range of electronic, optical, mechanical and thermoelectric characteristics. Direct bandgap acquired by the WC-GGA (TB[Formula: see text][Formula: see text][Formula: see text]mBJ) approach is 1.07[Formula: see text]eV (2.26[Formula: see text]eV), 0.61[Formula: see text]eV (1.71[Formula: see text]eV), 0.76[Formula: see text]eV (1.68[Formula: see text]eV), and 0[Formula: see text]eV (0.78[Formula: see text]eV) for KMgP, KMgAs, KMgSb, and KMgBi, respectively. Threshold power [Formula: see text] of KMgX ([Formula: see text], As, Sb, and Bi), starts from 2.218, 1.701, 1.674, and 0.776[Formula: see text]eV, so they exhibit the distinct peaks at 4.014, 3.742, 3.388, and 3.197[Formula: see text]eV, correspondingly. Among these materials, the maximum value of Seebeck coefficient (S) has been attained at 300[Formula: see text]K. Specifically, KMgP achieves the highest value of S at 3.134[Formula: see text]mV/K, followed by KMgAs at 2.947[Formula: see text]mV/K, KMgSb at 2.893[Formula: see text]mV/K, and KMgBi at 1.431[Formula: see text]mV/K, all in their respective p-type configurations. In order to determine the compound’s stability, we will explore the elastic and thermodynamic properties. We will also discuss their possible applications in photovoltaic and thermoelectric devices.
V. Rajpoot, , B. Das, V. Rajput, A. S. Verma, , , and
Virtual Company of Physics
In the current study, the moisture-sensing properties of three Copper (1%) doped Zinc Oxide nanomaterials, CZ-1, CZ-2, and CZ-3, are examined. These substances were created by solid-state interactions involving Cu2O and ZnO, CuO and ZnO, and, separately, Cu and ZnO. After four hours of annealing at 700°C for each of the three pellet samples, humidity-sensing tests were conducted. Throughout the whole range of relative humidity percent (15-90%RH) at room temperature, it was observed that the electrical resistance of all three nanomaterials reduced steadily. Powder x-ray diffractometer and scanning electron microscopy analyses were performed on the nanomaterial pellets to determine their crystallinity, structural phases (gross crystal structure), and surface morphology. Both the Scherer's approach and the Williamson and Hall's method were used to determine the crystallite size of the three samples, CZ-1, CZ-2, and CZ-3. The CZ-3 sample annealed at 700°C had the lowest crystallite size (36 nm) and the highest humidity sensitivity of the three samples.
S. Pal, , D. Sharma, M. Chandra, M. Mittal, P. Singh, M. Lal, A. S. Verma, , ,et al.
Virtual Company of Physics
In this paper, we present thermodynamic properties such as heat of formation, heat of fusion and entropy of fusion for chalcopyrite structured solids with the product of ionic charges and nearest neighbour distance d (Å). The heat of formation (∆Hf) of these compounds exhibit a linear relationship when plotted on a log-log scale against the nearest neighbour distance d (Å), but fall on different straight lines according to the ionic charge product of the compounds. On the basis of this result two simple heat of formation (∆Hf)heat of fusion (∆HF), and heat of formation (∆Hf)entropy of fusion (∆SF), relationship are proposed and used to estimate the heat of fusion (∆HF) and entropy of fusion (∆SF) of these semiconductors. We have applied the proposed relation to AIIBIVC2 V and AI BIIIC2 VI chalcopyrite semiconductor and found a better agreement with the experimental data than the values found by earlier researchers. The results for heat of formation differ from experimental values by the following amounts: 0.3% (CuGaSe2), 6.7% (CuInSe2), 5% (AgInSe2), 5% (ZnGeP2), 6% (ZnGeP2), 0.4% (ZnSnP2), 0.7% (ZnSiAs2), 2.6% (ZnGeAs2), 1.2% (ZnSnAs2), 3.8% (CdGeP2), 6.4% (CdGeAs2), the results for heat of fusion differ from experimental values by the following amounts: 2.6% (CuGaS2), 0.6% (CuInTe2), 6% (ZnGeAs2), 8.8% (ZnSiAs2) and the results for entropy of fusion differ from experimental values by the following amounts: 6% (CuInSe2), 8% (CdSiP2).
C.V. Sudheep, Arunima Verma, Priya Jasrotia, Jehova Jire L. Hmar, Rajeev Gupta, Ajay Singh Verma, Jyoti, Ashish Kumar, and Tanuj Kumar
Elsevier BV
Jitendra Kumar Bairwa, Peeyush Kumar Kamlesh, Upasana Rani, Rashmi Singh, Rajeev Gupta, Sarita Kumari, Tanuj Kumar, and Ajay Singh Verma
Elsevier BV
Samah Al‐Qaisi, Habib Rached, Tahani A. Alrebdi, S. Bouzgarrou, Debidatta Behera, Sanat Kumar Mukherjee, Mohamed Khuili, Mohamed Adam, Ajay Singh Verma, and Mohammed Ezzeldien
Wiley
AbstractThe double perovskites are become the emerging aspirant to fulfill the demand of energy. Therefore, the optoelectronic, elastic and transport characteristics of Ba2XMoO6 (X = Zn, Cd) are addressed systemically. The elastic constants show the mechanical stability. The nature of Ba2ZnMoO6 is brittle and Ba2CdMoO6 is ductile with large values of Debye temperature covalent bonding. The electronic band structures exhibit band gaps of 2.81 and 2.98 eV, which increase their importance for optoelectronic applications. The absorption of light energy, optical loss, refractive index, polarization of light energy are addressed in the energy range zero to 14 eV. Furthermore, thermoelectric characteristics are computed against chemical potentials at 300, 600, and 900 K. The chemical potential decides the p‐type nature, with holes as majority carriers. The increasing temperature increases the power factor and figure of merit. Therefore, the optoelectronic and thermoelectric characteristics reveals the importance of studied DPs for energy applications.
Jitendra Kumar Bairwa, Monika Rani, Peeyush Kumar Kamlesh, Rashmi Singh, Upasana Rani, Samah Al-Qaisi, Tanuj Kumar, Sarita Kumari, and Ajay Singh Verma
Springer Science and Business Media LLC
Pallavi, Chandravir Singh, Peeyush Kumar Kamlesh, Rajeev Gupta, and Ajay Singh Verma
Springer Science and Business Media LLC
Samah Al-Qaisi, Habib Rached, Malak Azmat Ali, Zeesham Abbas, Tahani A. Alrebdi, Khaild I. Hussein, Mohamed Khuili, Nasir Rahman, Ajay Singh Verma, Mohammed Ezzeldien,et al.
Springer Science and Business Media LLC
Upasana Rani, Peeyush Kumar Kamlesh, Tarun Kumar Joshi, Rashmi Singh, Samah Al-Qaisi, Rajeev Gupta, Tanuj Kumar, and Ajay Singh Verma
Springer Science and Business Media LLC
Upasana Rani, Peeyush Kumar Kamlesh, Tarun Kumar Joshi, Rashmi Singh, Sheetal Sharma, Rajeev Gupta, Tanuj Kumar, and Ajay Singh Verma
Elsevier BV
R. Singh, S. Kimothi, M. V. Singh, U. Rani, and A. S. Verma
Virtual Company of Physics
In this research paper, we have prepared thin film of MoS2 by thermal evaporation technique and characterized it. This thin film depositions lead to amorphous thin film. To make it crystalline, thermal annealing of the film have deposited on the substrates at 800 o C for two hour under vacuum environment. X-ray diffraction data of thin film shows the poly-crystalline nature. The Atomic Force Microscopy (AFM) image of the thin film shows the crystallinity with regularly arranged grains. Furthermore, an unconventional MoS2 based FET device has been fabricated by depositing thin film of MoS2 on p-type silicon. Thereafter, its transfer and output characteristics have been studied. The results show n-type semiconductor behaviour with an on/off ratio of about 103 and field-effect mobility of ~0.015 cm2/V. s at VDS of 1 V.
Monika Rani, Peeyush Kumar Kamlesh, Sunil Kumawat, Anuradha, Upasana Rani, Gunjan Arora, and Ajay Singh Verma
The Electrochemical Society
In the present research work, we have examined the variations in the structural, electronic, optical, thermoelectric, and thermodynamic properties of mixed halide perovskites, RbPbBr3-xIx (x = 0 to 3) by utilizing the FP-LAPW approach in the WIEN2k code within the GGA-PBE for exchange-correlation functionals. The orthorhombic halides RbPbBr3-xIx are found to exhibit direct band gap semiconducting character with band gap between 2 and 3 eV, as consensus with available experimental and theoretical results for the RbPbBr3 and RbPbI3 compounds. The thermal stability of these materials are confirmed by the thermodynamic results obtained by Gibbs approximations. Moreover, optical parameters for RbPbI3 are higher than those for other halide perovskites; encouraging its use for photovoltaic applications. The thermoelectric parameters of these materials are investigated at 300, 600, and 900 K, which reveals that RbPbIBr2 is the most efficient for thermoelectric devices among the other investigated materials.