Excited state dynamics at the nanoscale requires treatment of systems involving hundreds and thousands atoms. In majority cases, depending on process under investigation, electronic structure component calculation constitutes computation bottleneck. We developed an efficient approach for simulating nonadiabatic molecular (NA-MD) large in framework self-consistent charge density functional tight binding (SCC-DFTB) method. SCC-DFTB is combined with fewest switches surface hopping (FSSH)...

The search for an efficient electrode material based on 2D materials Li/Na-ion rechargable batteries is emerging field of research in the recent times. By employing density functional theory (DFT) calculations, we herein proposed a porous boron phosphide (p-BP) monolayer having superior electronic conductivity and enough thermodynamic stability as excellent cathode batteries. We have analyzed structure, stability, structure p-BP addressed adsorption Li/Na atoms over followed by charge...

Photocatalytic water splitting to spontaneously produce H2 and O2 is a long-standing goal in solar energy conversion, presenting significant challenge without using sacrificial electron donors or external biases. Inspired by natural photosynthesis, the design of artificial Z-scheme photocatalytic systems at forefront this field. These achieve higher redox potential separating photogenerated electrons holes through fast interlayer recombination process between valence conduction band edges....

The electronic structure and optical properties of fused S,N-heteroacenes (SNn, SN5–SN10) have been studied theoretically. calculations reveal that, bond length alteration approaches zero with increasing number heterocyclic rings in the conjugated molecules. As a general trend property, absorption maximum is red-shifted conjugation length, achieved through degree polymerization or by incorporating strong electron withdrawing groups at two ends However, an even–odd relationship observed...

Carbon nanotubes (CNTs) are appealing candidates for solar and optoelectronic applications. Traditionally used as electron sinks, CNTs can also perform donors, exemplified by coupling with perylenediimide (PDI). To achieve high efficiencies, transfer (ET) should be fast, while subsequent charge recombination slow. Typically, defects considered detrimental to material performance because they accelerate energy losses. We demonstrate that, surprisingly, common CNT improve rather than...

In search of an efficient solar energy harvester, we herein performed a time domain density functional study coupled with nonadiabatic molecular dynamics (NAMD) simulation to gain atomistic insight into the charge carrier graphitic carbon nitride (g-CN)-tungsten telluride (WTe2) van der Waals heterostructure. Our NAMD predicted ultrafast electron (589 fs) and hole-transfer (807 in g-CN/WTe2 heterostructure delayed electron-hole recombination process (2.404 ns) as compared that individual...

Here, we perform a time domain density functional study in conjunction with non-adiabatic molecular dynamics (NAMD) simulation to investigate the charge carrier series of van der Waals heterostructures made two-dimensional (2D) SnX2 (X = S or Se)-supported ZrS2, ZrSe2, and ZrSSe monolayers. Results from NAMD reveal delayed electron-hole recombination (in range 0.53-2.13 ns) ultrafast electron/hole transfer processes (electron within 108.3-321.5 fs hole between 107.6 258.8 fs). The most...

By using the self-consistent charge density functional tight binding method we studied electronic structure of ZnO/ZnS core/shell nanowire as a function both core radius and shell thickness. studying band energy alignment, structure, states, edge wave functions envisage efficacy this particular nano heterostructure in dye sensitized solar cell. The strong localization valence maximum conduction minimum ZnS ZnO core, respectively, irrespective thickness clearly indicates spatial separation...

Quasi-two-dimensional colloidal nanoplatelets (NPLs) have recently emerged as a class of semiconductor nanomaterials whose atomically precise monodisperse thicknesses give rise to narrow absorption and emission spectra. However, the sub-picosecond carrier dynamics NPLs at band edge remain largely unknown, despite their importance in determining optoelectronic properties these materials. Here, we use combination femtosecond transient spectroscopy nonadiabatic molecular simulations investigate...

Using first-principles calculations, we have studied the energetic feasibility and magnetic properties of transition metal (TM) doped PtSe2 monolayers. Our study shows that TM layers with 6.25% doping exhibit versatile spintronic behaviour depending on nature dopant atoms. Groups IVB VIII10 are non semiconductors, while groups IIIB, VB, VIII8, VIII9, IB half-metals finally, VIB, VIIB IIB spin polarized semiconductors. The presence half-metallic semiconducting characteristics suggest can be...

Recently, inorganic–organic hybrid perovskites have gained immense attention in view of its outstanding performance solar cell devices. Due to the toxicity lead, lead-free are highly desirable order achieve comparable or superior photovoltaic performance. In this study, we investigated structural, electronic, and optical properties lead free two-dimensional CH3NH3Sn(1 – x)GexI3 (0 ≤ x 0.5) perovskites. These direct band gap semiconductors possess region 1.38–1.61 eV, which for energy...

Charge separation is at the heart of solar energy applications, and efficient materials require fast photoinduced electron transfer (ET) slow charge recombination (CR). Using time-dependent self-consistent density functional tight-binding theory combined with nonadiabatic (NA) molecular dynamics, we report a detailed analysis ET CR in hybrids composed photoactive covalent organic polyhedra (COP) encapsulated fullerenes. The occurs on subpicosecond time scale accelerates increasing fullerene...

Porphyrin nanorings get enormous attention as potential photovoltaic materials due to their unique and tunable optoelectronic properties. Distribution of charge in porphyrin can alter the performance. We investigate photodynamics two nanorings, i.e., fused meso observe role delocalization on carrier relaxation dynamics. Employing nonadiabatic molecular dynamics within framework density functional tight binding theory, we demonstrate that nanoring exhibits six times longer exciton lifetime...

Laser-initiated decomposition of carbon nanotubes (CNTs) can lead to medical, military, and other applications. In medicine, CNTs give rise efficient remedies against diseases malignant cells, since they encapsulate drug molecules, be delivered inside living organisms, absorb light that penetrates through biological tissues. As explosives, pyrotechnics, propellants, activated remotely by a visible or infrared laser, avoiding the need for detonating cord. The reported non-equilibrium...

In this article, we propose a new two-dimensional ${\mathrm{CP}}_{3}$ material with distinguished properties from comprehensive first-principles calculations. It has excellent thermal, mechanical, and dynamical stabilities promise for experimental fabrication. The low cleavage energy ($0.57\phantom{\rule{4pt}{0ex}}\mathrm{J}/{\mathrm{m}}^{2}$) implies the plausibility of single-layer exfoliation bulk structure. Other than exfoliation, predict an alternative route to synthesize monolayer...

Parameters for CdX, SeX, and TeX (X = H, C, N, O, S, Se, Te, Cd) have been generated within the self-consistent-charge density-functional tight-binding (SCC-DFTB) framework. The approach has tested against ab initio theory calculations relevant bulk phases, surfaces, nanowires, small molecular systems. SCC-DFTB reproduces structural, electronic, energetic properties very well, demonstrating that developed parameters are fully transferable among different chemical environments.

By using computational methodologies based on time dependent density functional theory (TDDFT) we study the opto-electronic properties of three types triphenylamine (TPA)-based dyes, namely TPA-TBT-1, TPA-DBT-1, and TPA-BT-1, these are proposed as potential candidates for photovoltaic applications. Energy band modulation has been performed by functionalizing dyes with different electron donating withdrawing groups. Photoelectron spectra have investigated a combination DFT TDDFT approaches....

Many-particle Auger-type processes are common in nanoscale materials due to a combination of high densities states that can support multiple excitations and substantial Coulomb coupling between charges enhanced by quantum confinement. Auger decay dynamics (10,5) semiconductor carbon nanotubes (CNT) with different aspect ratios particle simulated time domain using global flux surface hopping, recently developed implemented within Kohn-Sham tight-binding density functional theory. Despite an...

Recent experiments on CdSe nanoplatelets synthesized with precisely controlled thickness that eliminates ensemble disorder have allowed accurate measurement of quantum coherence at room temperature. Matching exactly the cores experimentally studied particles and considering several defects, we establish atomistic origins loss between heavy light hole excitations in two-dimensional CdSe/CdZnS core/shell structures. The times obtained using molecular dynamics based tight-binding density...

Understanding the dynamics of photogenerated charge carriers is essential for enhancing performance solar and optoelectronic devices. Using atomistic quantum simulations, we demonstrate that a short π-conjugated optically active template can be used to control hot carrier relaxation, separation, recombination in light-harvesting porphyrin nanorings. Relaxation holes slowed by 60% with an compared analogous inactive template. Both systems exhibit subpicosecond electron transfer from...

Porphyrin nanoring has been attracting immense attention due to its light harvesting capacity and potential applications in optical, catalysis, sensor, electronic devices. We demonstrate by nonadiabatic quantum dynamics simulations that the photovoltaic efficiency can be enhanced template engineering. Altering hexadentate (T6) with two tridentate templates (2T3) within porphyrin ring (P6) cavity accelerated electron transfer twice suppressed electron–hole recombination nearly three times....

By making use of a density-functional tight-binding (DFTB) method we studied the electronic and optical properties ZnSe/ZnS ZnS/ZnSe core/shell nanoparticles. Our emphasis will be on atomic charge distribution, energy levels, band gap, excitation spectra, their variation with thickness shell for both systems. We have made qualitative comparison our theoretical results those experimental observation these Finally, energetics diffusion one Se(S) S(Se) atoms between core in nanostructures to...

The structural and electronic properties of (100) faceted CdTe nanowires with hexagonal or triangular cross sections were investigated using the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. formation energies band gap are studied as a function both nanowire size surface atom ratio. atomic relaxations compared corresponding surface. strain was eliminated by passivating dangling bonds hydrogen atoms. passivation has only little influence on resulting in an...