Metal halide perovskites (MHPs) have attracted attention because of their high optoelectronic performance that is fundamentally rooted in the unusual properties MHP defects. By developing an ab initio-based machine-learning force field, we sample structural dynamics MHPs on a nanosecond time scale and show vacancies create midgap trap states bulk but not surface. Deep traps result from Pb-Pb dimers can form across vacancy only bulk. The required shortening distance by nearly 3 Å facilitated...

Quantum tunneling, a phenomenon that allows particles to pass through potential barriers, can play critical role in energy transfer processes. Here, we demonstrate the proper design of organic–inorganic interfaces two-dimensional (2D) hybrid perovskites for efficient triplet (TET), where quantum tunneling excitons is key driving force. By employing temperature-dependent and time-resolved photoluminescence pump–probe spectroscopy techniques, establish from inorganic lead-iodide sublattices...

Lead-free double perovskites hold promise for stable and environmentally benign solar cells; however, they exhibit low efficiencies because defects act as charge recombination centers. Identifying trap-assisted loss mechanisms developing defect passivation strategies constitute an urgent goal. Applying unsupervised machine learning to density functional theory nonadiabatic molecular dynamics, we demonstrate that negatively charged Br vacancies in Cs2AgBiBr6 create deep hole traps through...

Tin-based two-dimensional (2D) perovskites are emerging as lead-free alternatives in halide perovskite materials, yet their exciton dynamics and transport remain less understood due to defect scattering. Addressing this, we employed temperature-dependent transient photoluminescence (PL) microscopy investigate intrinsic three structurally analogous Sn- Pb-based 2D perovskites. Employing conjugated ligands, synthesized high-quality crystals with enhanced phase stability at various...

The hot phonon bottleneck has been under intense investigation in perovskites. In the case of perovskite nanocrystals, there may be bottlenecks as well quantum bottlenecks. While they are widely assumed to exist, evidence is growing for breaking potential both forms. Here, we perform state-resolved pump/probe spectroscopy (SRPP) and time-resolved photoluminescence (t-PL) unravel exciton relaxation dynamics model systems bulk-like 15 nm nanocrystals CsPbBr3 FAPbBr3, with FA being...

Understanding the sub-band gap luminescence in Ruddlesden–Popper 2D metal halide hybrid perovskites (2D HaPs) is essential for efficient charge injection and collection optoelectronic devices. Still, its origins are still under debate with respect to role of self-trapped excitons or radiative recombination via defect states. In this study, we characterized separation, recombination, transport single crystals, exfoliated layers, polycrystalline thin films butylammonium lead iodide (BA2PbI4),...

Lead-free vacancy-ordered halide perovskites (VOHPs) are emerging as promising materials for environmentally friendly next-generation optoelectronic devices. However, a detailed atomistic understanding of charge carrier dynamics under ambient conditions ( 300 K) is lacking. Thus, attempts to refine the performance VOHPs through material selection remain challenging. Here, we combine non-adiabatic molecular dynamics, time-domain density functional theory, and an unsupervised machine learning...

Ternary I-III-VI2 semiconductors, such as CuInSe2, exhibit diverse polymorphs with unique structural characteristics and optoelectronic properties. This study investigates the pressure-induced phase transitions of metastable wurtzite-like CuInSe2 nanocrystals. Using a combination synchrotron X-ray diffraction, pair distribution function analysis, density functional theory calculations, we reveal transition from cation-ordered (Pmc21) to cation-disordered NaCl-like (Fm3̅m) structures at 7.7...

Hot exciton relaxation dynamics is one of the main processes in quantum dots (QD), conferring their functions optoelectronic devices spanning photovoltaics and solar fuel generation to light emitting diodes, lasers, sources. The challenge has been monitor energy parallel with resolution excitation or excess energy. Here, we exploit unique capacity Coherent Multi-Dimensional Spectroscopy (CMDS) provide first observation hot cooling landscape a large size range CsPbBr3 lead halide perovskite...

Two-dimensional Ruddlesden–Popper (RP) halide perovskites stand out as excellent layered materials with favorable optoelectronic properties for efficient light-emitting, spintronic, and other spin-related applications. However, often determined by defects are not well understood in these perovskite systems. This work investigates the ground state electronic structure of commonly formed a typical RP density functional theory. Our study reveals that 2D generally retain their defect tolerance...

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...

The study exhibits the beneficial effect of A-cation mixing in hybrid halide perovskites for efficient hot carrier harvesting.

The decay of excited states via radiative and nonradiative paths is well understood in molecules bulk semiconductors but less so nanocrystals. Here, we perform time-resolved photoluminescence (t-PL) experiments on CsPbBr3 metal-halide perovskite nanocrystals, with a time resolution 3 ps, sufficient to observe the both excitons biexcitons as function temperature. striking result that rate constant single exciton increases at low temperatures an exponential functional form, suggesting quantum...

CsPbBr3 quantum dots (QDs) have been recently suggested for their application as bright green light-emitting diodes (LEDs); however, optical properties are yet to be fully understood and characterized. In this work, we utilize time-dependent density functional theory analyze the ground excited states of clusters in presence various low formation energy vacancy defects. Our study finds that QD perovskites retain defect tolerance with limited perturbance simulated UV–vis spectra. The exception...

The idea that the electronic transition dipole moment does not depend upon nuclear excursions is Condon approximation and central to most spectroscopy, especially in solid state. We show a strong breakdown of time-resolved photoluminescence from CsPbBr3 metal halide perovskite semiconductor nanocrystals. Experiments reveal increases on 30 ps time scale due structural dynamics lattice. Ab initio molecular calculations quantitatively reproduce experiments by considering excitation-induced dynamics.

Metal halide perovskites constitute a new type of semiconducting materials with long charge carrier lifetimes and efficient light-harvesting. The performance perovskite solar cells related devices is limited by nonradiative energy losses, facilitated defects. Combining nonadiabatic molecular dynamics time-domain density functional theory, we demonstrate that losses depend strongly on the defect chemical state. By considering an extra Pb atom in CH3NH3PbI3, which common lead perovskites,...

The drive to develop new organic materials for use in optoelectronic devices has created the need understand fundamental role functionalization plays concerning electronic properties of conjugated molecules. Here density functional theory (DFT) is used investigate how HOMO-LUMO gaps halogenobenzenes are affected as a function substituent size, position, electronegativity, ionization potential, and polarizability. A detailed molecular orbital analysis also provided. It shown that static...

The functionality of multicomponent self-assembled monolayers (SAMs) can be severely diminished by the segregation like components into nanoscale domains, a process that maximizes favorable short-range intermolecular interactions. Here, we explore use modular family sulfur-functionalized metal bis(terpyridine) complexes ([M(tpy-R)2]2+(PF6–)2) to prepare mixed SAMs, considering comparable structure, dimensions, and ionic composition these species should render them interchangeable within...

Wide band gap AInSe2 (A = K, Rb, Cs) is an important interlayer material for improving the efficiency of Cu(In,Ga)(S,Se)2 (CIGS) solar cells. Compared to high-vacuum deposition and solid-state synthesis, a less energy-intensive method interest its fabrication. Herein, we present rapid, low-temperature colloidal synthesis nanocrystals that opens pathway convenient solution processing. The crystal structures electronic were studied, their particle morphology was found be dependent on choice...

A P162– polyphosphide dianion ink was produced by the reaction of red phosphorus with a binary thiol–amine mixture ethanethiol (ET) and ethylenediamine (en). The identified solution 31P NMR spectroscopy electrospray ionization mass spectrometry. This solute compared to products white (P4) other elemental pnictides in same solvent system. P4 ET en gives polyphosphide; however, easier handling lower reactivity highlights novelty that reaction. Elemental arsenic antimony both give mononuclear...

Understanding the adsorption of organic molecules on metals is important in numerous areas surface science, including electrocatalysis, electrosynthesis, and biosensing. While thiols are commonly used to tether metals, it desirable broaden range anchoring groups. In this study, we use a combined spectroelectrochemical computational approach demonstrate 4-cyanophenols (CPs) polycrystalline gold. Using nitrile stretching vibration as marker, confirm CP gold electrode compare our results with...

There is increasing demand for tailored molecular inks that produce phase-pure solution-processed semiconductor films. Within the Cu-Sn-S phase space, Cu2SnS3 belongs to I2-IV-VI3 class of semiconductors crystallizes in several different polymorphs. We report ability thiol-amine solvent mixtures dissolve inexpensive bulk Cu2S and SnO precursors generate free-flowing inks. Upon mild annealing, polymorphic control over tetragonal (I4̅2m) orthorhombic (Cmc21) films was realized simply by...

The functionality of multicomponent self-assembled monolayers (SAMs) can be severely diminished by the segregation like components into nanoscale domains, a process that maximizes favorable short-range intermolecular interactions. Here, we explore use modular family sulfur-functionalized metal bis(terpyridine) complexes ([M(tpy-R)