Detrimental Defect Cooperativity at TiO₂/CH₃NH₃PbI₃ Interface: Decreased Stability, Enhanced Ion Diffusion, and Reduced Charge Lifetime and Transport

ACS Energy Letters, Год журнала: 2024, Номер unknown, С. 5888 - 5897

Опубликована: Ноя. 18, 2024

Interfaces are essential for solar cell performance since they govern charge separation and transport. Using quantum dynamics simulation, we demonstrate that at interfaces, common defects benign on their own, iodine vacancy in CH3NH3PbI3 (VI) oxygen TiO2 (VO), responsible synergistically poor stability losses. VO promotes VI diffusion accelerates migration. A midgap trap state appears, inhibiting transport accelerating recombination by an order of magnitude. Strong structural distortions strengthen electron-vibrational interactions activate high-frequency phonons. Because the widely reported high defect-tolerance lead-halide perovskites, synergistic detrimental influence perovskite with other materials is often overlooked. The interfacial defect pairing could be a major reason losses cells. results suggest either high-quality or extraction layer may sufficient to achieve performance.

Язык: Английский

---

Anion Doping Delays Nonradiative Electron–Hole Recombination in Cs-Based All-Inorganic Perovskites: Time Domain ab Initio Analysis

The Journal of Physical Chemistry Letters, Год журнала: 2022, Номер 13(49), С. 11375 - 11382

Опубликована: Дек. 1, 2022

Using time-domain density functional theory combined with nonadiabatic (NA) molecular dynamics, we demonstrate that composition engineering of the X-site anions has a strong influence on nonradiative electron–hole recombination and thermodynamic stability cesium-based all-inorganic perovskites. Partial substitution iodine(I) bromine (Br) acetate (Ac) reduces NA electron–vibrational coupling by minimizing overlap between electron hole wave functions suppressing atomic fluctuations. The doping also widens energy gap to further reduce enhance open-circuit voltage perovskite solar cells. These factors increase charge carrier lifetime an order magnitude improve structural in series CsPbI1.88BrAc0.12 > CsPbI2Br CsPbI3. fundamental atomistic insights into anion photophysical properties lead halide perovskites guide design efficient optoelectronic materials.

Язык: Английский

---

How the Stacking Pattern Influences the Charge Transfer Dynamics of van der Waals Heterostructures: An Answer from a Time-Domain Ab Initio Study

The Journal of Physical Chemistry Letters, Год журнала: 2023, Номер 14(34), С. 7672 - 7679

Опубликована: Авг. 21, 2023

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 interesting finding our is that switching AB AA stacking extends lifespan by significant amount. because pattern can be rationalized weak electron-phonon coupling, lower coupling (NAC), fast decoherence time. Thus, these insightful studies excited carriers variation an effective tool develop efficient photovoltaic devices based on 2D heterostructures.

Язык: Английский

---

Ion Migration at Metal Halide Perovskite Grain Boundaries Elucidated with a Machine Learning Force Field

The Journal of Physical Chemistry Letters, Год журнала: 2024, Номер unknown, С. 12362 - 12369

Опубликована: Дек. 9, 2024

Metal halide perovskites are promising optoelectronic materials with excellent defect tolerance in carrier recombination, believed to arise largely from their unique soft lattices. However, weak lattice interactions also promote ion migration, leading serious stability issues. Grain boundaries (GBs) have been experimentally identified as the primary migration channels, but relevant mechanism remains elusive. Using molecular dynamics a machine learning force field, we directly model at common CsPbBr3 GB. We demonstrate that as-built GB model, containing 6400 atoms, experiences structural reconstruction over several nanoseconds, and only Br atoms diffuse after that. A fraction of near either migrate toward center or along through different channels. Increasing temperature not accelerates via Arrhenius activation allows more migrate. The energies much lower than bulk due large-scale distortions favorable non-stoichiometric local environments available GBs. Making composition stoichiometric by doping annealing can suppress migration. reported results provide valuable atomistic insights into properties metal perovskites.

Язык: Английский

---

Phase Segregation and Sequential Expulsion of Iodide and Bromide in Photoirradiated Ruddlesden–Popper 2D Perovskite Films

ACS Energy Letters, Год журнала: 2022, Номер 7(11), С. 3982 - 3988

Опубликована: Окт. 19, 2022

Two-dimensional (2D) Ruddlesden–Popper mixed-halide perovskite films, BA2PbBr2I2, undergo phase segregation when excited with visible light to generate bromide- and iodide-rich regions, as marked by absorption emission changes. Upon stopping illumination, the process reverses, allowing original film compositions be restored. However, if films are in contact dichloromethane, irradiation causes sequential expulsion of iodide bromide introduces irreversible changes 2D films. The disappearance I– Br– from pristine (BA2Pb2Br4 BA2Pb2I4) under photoirradiation, observed variances rates, reflects differences halide ion mobilities these photoinstability raises questions about their use stabilizing bulk, three-dimensional (3D) solar cells through 3D/2D interfaces.

Язык: Английский

---