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Interplay between Iodide and Tin Vacancies in CsSnI<sub>3</sub> Perovskite Solar Cells
Rajendra Kumar, G.,Kim, Hee-Je,Karupannan, Senthil,Prabakar, Kandasamy American Chemical Society 2017 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.121 No.30
<P>Tin -based perovskite materials have the drawbacks of high density of Sn vacancies, structural deformations of SnI6- octahedra, and oxidation of unstable Sn2+ states, resulting in poor chemical stability processed at inert and open atmosphere. In this work, we demonstrate the temperature effects on reduction of Sn vacancies (V-sn) in polymorphic CsSnI3 perovskite solar cells. Evidence of light-induced I- ion diffusion and an interplay between iodide and Sn vacancies were briefly presented. We have observed by X-ray photoelectron spectroscopy that the formation of iodide vacancies (V-I) are highly activated at 60 degrees C, contributing to the reduction of acceptor defects, mainly Sn vacancies (V-sn). The formation of SnO- and SnO2- at high temperature mitigates the Sn-I interaction and eventually increases the trap density at Au/CsSnI3 interfaces. We have observed by time-of-flight secondary ion mass spectrometry that the delocalized r ions are accumulated near the metal contacts and form AuI- ions which diffuse through the material, inhibiting the exciton transport.</P>
( Rajendra Kumar Sahoo ),( Abhijit S. Nair ) 대한통증학회 2015 The Korean Journal of Pain Vol.28 No.4
Anterior cutaneous nerve entrapment syndrome (ACNES) is one the most common cause of chronic abdominal wall pain. The syndrome is mostly misdiagnosed, treated wrongly and inadequately. If diagnosed correctly by history, examination and a positive carnett test, the suffering of the patient can be relieved by addressing the cause i.e. local anaesthetic with steroid injection at the entrapment site. Conventionally, the injection is done by landmark technique. In this report, we have described 2 patients who were diagnosed with ACNES who were offered ultrasound guided transverses abdominis plane (TAP) injection who got significant pain relief for a long duration of time. (Korean J Pain 2015; 28: 284-286)
Phase transition kinetics and surface binding states of methylammonium lead iodide perovskite
Rajendra Kumar, G.,Dennyson Savariraj, A.,Karthick, S. N.,Selvam, S.,Balamuralitharan, B.,Kim, Hee-Je,Viswanathan, K. K.,Vijaykumar, M.,Prabakar, Kandasamy The Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.10
<P>We have presented a detailed analysis of the phase transition kinetics and binding energy states of solution processed methylammonium lead iodide (MAPbI(3)) thin films prepared at ambient conditions and annealed at different elevated temperatures. It is the processing temperature and environmental conditions that predominantly control the crystal structure and surface morphology of MAPbI3 thin films. The structural transformation from tetragonal to cubic occurs at 60 degrees C with a 30 minute annealing time while the 10 minute annealed films posses a tetragonal crystal structure. The transformed phase is greatly intact even at the higher annealing temperature of 150 degrees C and after a time of 2 hours. The charge transfer interaction between the Pb 4f and I 3d oxidation states is quantified using XPS.</P>
CONFORMAL SEMI-SLANT SUBMERSIONS FROM LORENTZIAN PARA SASAKIAN MANIFOLDS
Kumar, Sushil,Prasad, Rajendra,Singh, Punit Kumar Korean Mathematical Society 2019 대한수학회논문집 Vol.34 No.2
In this paper, we introduce conformal semi-slant submersions from Lorentzian para Sasakian manifolds onto Riemannian manifolds. We investigate integrability of distributions and the geometry of leaves of such submersions from Lorentzian para Sasakian manifolds onto Riemannian manifolds. Moreover, we examine necessary and sufficient conditions for such submersions to be totally geodesic where characteristic vector field ${\xi}$ is vertical.
A note on Einstein-like para-Kenmotsu manifolds
Rajendra Prasad,Sandeep Kumar Verma,Sumeet Kumar 호남수학회 2019 호남수학학술지 Vol.41 No.4
The objective of this paper is to introduce and study Einstein-like para-Kenmotsu manifolds. For a para-Kenmotsu manifold to be Einstein-like, a necessary and sufficient condition in terms of its curvature tensor is obtained. We also obtain the scalar curvature of an Einstein-like para-Kenmotsu manifold. A necessary and sufficient condition for an almost para-contact metric hypersurface of a locally product Riemannian manifold to be para-Kenmotsu is derived and it is shown that the para-Kenmotsu hypersurface of a locally product Riemannian manifold of almost constant curvature is always Einstein.
Quasi hemi-slant submanifolds of cosymplectic manifolds
Rajendra Prasad,Sandeep Kumar Verma,Sumeet Kumar,Sudhakar K Chaubey 강원경기수학회 2020 한국수학논문집 Vol.28 No.2
We introduce and study quasi hemi-slant submanifolds of almost contact metric manifolds (especially, cosymplectic manifolds) and validate its existence by providing some non-trivial examples. Necessary and sufficient conditions for integrability of distributions, which are involved in the definition of quasi hemi-slant submanifolds of cosymplectic manifolds, are obtained. Also, we investigate the necessary and sufficient conditions for quasi hemi-slant submanifolds of cosymplectic manifolds to be totally geodesic and study the geometry of foliations determined by the distributions.
CONFORMAL HEMI-SLANT SUBMERSIONS FROM ALMOST HERMITIAN MANIFOLDS
Kumar, Sumeet,Kumar, Sushil,Pandey, Shashikant,Prasad, Rajendra Korean Mathematical Society 2020 대한수학회논문집 Vol.35 No.3
In this paper, our main objective is to introduce the notion of conformal hemi-slant submersions from almost Hermitian manifolds onto Riemannian manifolds as a generalized case of conformal anti-invariant submersions, conformal semi-invariant submersions and conformal slant submersions. We mainly focus on conformal hemi-slant submersions from Kähler manifolds. During this manner, we tend to study and investigate integrability of the distributions which are arisen from the definition of the submersions and the geometry of leaves of such distributions. Moreover, we tend to get necessary and sufficient conditions for these submersions to be totally geodesic for such manifolds. We also provide some quality examples of conformal hemi-slant submersions.
Rajendra Kumar Konidena,임준섭,이준엽 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.107 No.-
Herein, we report a new molecular design based on carbazole for the development of high triplet energybipolar host materials for blue phosphorescent organic light emitting diodes (PhOLEDs). Two new isomerichost materials named, 11CzCzCN and 14CzCzCN were designed and synthesized by modifyingthe carbazole core with carbazole donor at C1 and cyano acceptor at C8-position. The effective interchromophoricelectronic communications between the attached donors and central carbazole were interruptedby virtue of large dihedral angle at C1 and short-axis linkage. Also, the strong charge transferinteractions between the donor at C1 and acceptor at C8 was hampered due to the broken conjugation. As a result, the compounds showed high triplet energy (ET) over 2.75 eV without compromising the bipolarcharge transporting property. Interestingly, computations and single carrier device analysis evidencedgood bipolar charge transporting ability for 11CzCzCN over its structural isomer 14CzCzCN. The applicabilityof these compounds as hosts for blue PhOLEDs was explored by using a well-known Flrpic dopant. The 11CzCzCN hosted device showed higher performance with maximum EQE of 20.6%, current efficiencyof 39.6 cd/A and efficiency roll off of 8.2% at 1000 cd/m2 over its analogue 14CzCzCN hosted device attributedto its high ET and balanced charge transporting property. We believe that this study would providevaluable insights for executing new molecular designs on carbazole for the development of efficient hostmaterials for blue PhOLEDs.