Structural Disorder in Higher-Temperature Phases Increases Charge Carrier Lifetimes in Metal Halide Perovskites

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(41), P. 19137 - 19149

Published: Oct. 7, 2022

Solar cells and optoelectronic devices are exposed to heat that degrades performance. Therefore, elucidating temperature-dependent charge carrier dynamics is essential for device optimization. Charge lifetimes decrease with temperature in conventional semiconductors. The opposite, anomalous trend observed some experiments performed MAPbI3 (MA = CH3NH3+) other metal halide perovskites. Using ab initio quantum simulation, we establish the atomic mechanisms responsible nonradiative electron-hole recombination orthorhombic-, tetragonal-, cubic MAPbI3. We demonstrate structural disorder arising from phase transitions as important due heating same phase. grow both increasing upon transition higher-temperature phases. increased lifetime rationalized by induces partial localization, decreases nonadiabatic coupling, shortens coherence. Inelastic elastic electron-vibrational interactions exhibit opposite dependence on localization arise thermal motions of inorganic lattice organic cations depend significantly deformations induced fluctuations order defects, hence, plays a very role. Since increases but inhibits transport, an optimal regime maximizing diffusion can be designed, depending phase, temperature, material morphology, architecture. atomistic enhanced at elevated temperatures provide guidelines design improved solar energy materials.

Language: Английский

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Intrinsic Dipole Arrangement to Coordinate Energy Levels for Efficient and Stable Perovskite Solar Cells

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(18)

Published: March 6, 2023

Despite great progress in perovskite photovoltaics, it should be noted that the intrinsic disorder dipolar cations organic-inorganic hybrid perovskites exert negative effects on energy band structure as well carrier separation and transfer dynamics. However, oriented polarization achieved by applying an external electric field may cause irreversible damage to perovskites. Herein, a unique efficient strategy is developed modulate dipole arrangement films for high-performance stable solar cells (PSCs). The spontaneous reorientation of cation methylamine triggered polar molecule, constructing vertical during crystallization regulation. determines gradient energy-level PSCs more favorable energetics at interfaces, effectively enhancing built-in suppressing nonradiative recombination. Besides, induces local dielectric environment remarkably reduce exciton binding energy, leading ultralong diffusion length up 1708 nm. Accordingly, n-i-p achieve significant increase power conversion efficiency, reaching 24.63% with negligible hysteresis exhibiting outstanding stabilities. This also provides facile route eliminate mismatched enhance dynamics other novel photovoltaic devices.

Language: Английский

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Tailoring Multifunctional Self‐Assembled Hole Transporting Molecules for Highly Efficient and Stable Inverted Perovskite Solar Cells

Advanced Functional Materials, Journal Year: 2023, Volume and Issue: 33(10)

Published: Jan. 29, 2023

Abstract The self‐assembled hole transporting molecules (SAHTMs) bearing anchoring groups have been established as the layers (HTLs) for highly efficient p–i–n perovskite solar cells (PSCs), yet their stability and engineering at molecular level remain challenging. A topological design of anisotropic aligned SAHTM‐based HTLs operationally stable PSCs that exhibit exceptional solar‐to‐electric power conversion efficiencies (PCEs) is demonstrated. judiciously designed multifunctional comprise donor–acceptor subunit phosphonic acid group anchoring, realizing face‐on π‐stacking parallel to transparent conductive oxide substrate. high affinity SAHTMs multi‐crystalline thin film benefits passivating buried interface, strengthening interfacial contact while facilitating transfer. Consequently, PSC devices are obtained with a champion PCE 23.24% outstanding operational toward various environmental factors including long‐term full sunlight soaking evaluated temperatures. Perovskite modules efficiency approaching 20% also fabricated an active device area above 17 cm 2 .

Language: Английский

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Rapid Interlayer Charge Separation and Extended Carrier Lifetimes due to Spontaneous Symmetry Breaking in Organic and Mixed Organic–Inorganic Dion–Jacobson Perovskites

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(9), P. 5297 - 5309

Published: Feb. 24, 2023

Promising alternatives to three-dimensional perovskites, two-dimensional (2D) layered metal halide perovskites have proven their potential in optoelectronic applications due improved photo- and chemical stability. Nevertheless, photovoltaic devices based on 2D suffer from poor efficiency owing unfavorable charge carrier dynamics energy losses. Focusing the Dion-Jacobson perovskite phase that is rapidly rising popularity, we demonstrate doping of complementary cations into 3-(aminomethyl)piperidinium accelerates spontaneous separation slows down recombination, both factors improving performance. Employing ab initio nonadiabatic (NA) molecular combined with time-dependent density functional theory, cesium broadens bandgap by 0.4 eV breaks structural symmetry. Assisted thermal fluctuations, symmetry breaking helps localize electrons holes different layers activates additional vibrational modes. As a result, accelerated. Simultaneously, lifetime grows shortened coherence time between ground excited states. The established relationships composition provide guidelines toward future material discovery design solar cells.

Language: Английский

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Understanding Defects in Perovskite Solar Cells through Computation: Current Knowledge and Future Challenge

Advanced Science, Journal Year: 2024, Volume and Issue: 11(20)

Published: March 19, 2024

Abstract Lead halide perovskites with superior optoelectrical properties are emerging as a class of excellent materials for applications in solar cells and light‐emitting devices. However, perovskite films often exhibit abundant intrinsic defects, which can limit the efficiency perovskite‐based optoelectronic devices by acting carrier recombination centers. Thus, an understanding defect chemistry lead assumes prominent role further advancing exploitation perovskites, which, to large extent, is performed relying on first‐principles calculations. complex structure, strong anharmonicity, soft lattice pose challenges studies. In this perspective, basis briefly reviewing current knowledge concerning computational studies work concentrates addressing unsolved problems proposing possible research directions future. This perspective particularly emphasizes indispensability developing advanced approaches deeply nature defects conducting data‐driven designing reasonable strategies improve performance applications. Finally, highlights that theoretical should pay more attention establishing close clear links experimental investigations provide useful insights scientific industrial communities.

Language: Английский

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Sub-bandgap charge harvesting and energy up-conversion in metal halide perovskites: ab initio quantum dynamics

npj Computational Materials, Journal Year: 2025, Volume and Issue: 11(1)

Published: Jan. 11, 2025

Metal halide perovskites (MHPs) exhibit unusual properties and complex dynamics. By combining ab initio time-dependent density functional theory, nonadiabatic molecular dynamics machine learning, we advance quantum simulation to nanosecond timescale demonstrate that large fluctuations of MHP defect energy levels extend light absorption longer wavelengths enable trapped charges escape into bands. This allows low photons contribute photocurrent through up-conversion. Deep can become shallow transiently vice versa, altering the traditional classification deep. While fluctuate more in MHPs than semiconductors, some levels, e.g., Pb interstitials, remain far from band edges, acting as charge recombination centers. Still, many defects deemed detrimental based on static structures, are fact benign The extended harvesting up-conversion provide strategies for design novel solar, optoelectronic, information devices.

Language: Английский

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Hole Trapping in Halide Perovskites Induces Phase Segregation

Accounts of Materials Research, Journal Year: 2022, Volume and Issue: 3(7), P. 761 - 771

Published: June 29, 2022

ConspectusMetal halide perovskites have garnered a great deal of attention for their applications in photovoltaics, LEDs, and radiation detection. The ease solution processing high-quality perovskite semiconductors with large absorption coefficients tolerance to native defects is decidedly attractive. Additionally, the ability precisely tune band gap through compositional alloying ion particular interest range applications, especially tandem solar cells. However, under steady state light irradiation, an initially homogeneous mixed (MHP) will form local domains that are rich one (e.g., Br or I). This light-induced phase segregation MHPs forms iodide-rich act as charge carrier traps lowers efficiency perovskite-based devices. Thus, poses serious challenge implementation real-world device settings. Interestingly, when segregated MHP film placed dark, entropic driving forces become dominant remixes returns its state. Several key mechanistic details been elucidated over years. there still aspects not clear, ongoing debate literature what factors contribute mechanism.This Account discusses recent results point specific role hole trapping segregation. generation holes above-band-gap excitation electrochemical injection increases migration leads thermodynamic redox properties provide strong force oxidation iodide species MHPs. mobile within lattice take time migrate generate halide-rich domains. When contact nonpolar solvent, iodine further extended expulsion from film. mobility halides susceptibility hole-induced play crucial determining long-term stability metal perovskites. Strategies gain kinetic control slow needed overcome these hurdles achieve stable Modification composition introduction different cations ions, low-dimensional phases may suppress achieving improving cells emitting devices minimal impacts, suppression remains factor.

Language: Английский

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Transition from Capacitive to Inductive Hysteresis: A Neuron-Style Model to Correlate I–V Curves to Impedances of Metal Halide Perovskites

The Journal of Physical Chemistry C, Journal Year: 2022, Volume and Issue: 126(32), P. 13560 - 13578

Published: Aug. 4, 2022

Metal halide perovskite (MHP) devices often show different types of hysteresis in separate voltage domains. At low voltage, the impedance response is capacitive, and cell gives regular hysteresis. high inverted, corresponding to an inductive that causes a negative capacitance feature. We calculate current due chemical inductor model, we inversely proportional scan rate. formulate general dynamical model for solar style neuronal models action potential, based on few differential equations. The allows us track transition from capacitive properties, both by spectroscopy current–voltage measurements at sweep rates. obtain correlation time constants capacitor inductor. interpret origin low-frequency features terms ion-controlled surface recombination. This explains strong inductor, as originate same mechanism. methodology derived this paper provides great control over dynamic properties metal cells, even cases which there are qualitative changes broad range.

Language: Английский

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A Universal Grain “Cage” to Suppress Halide Segregation of Mixed-Halide Inorganic Perovskite Solar Cells

ACS Energy Letters, Journal Year: 2022, Volume and Issue: 7(10), P. 3467 - 3475

Published: Sept. 16, 2022

Bandgap-tunable mixed-halide perovskites offer exciting opportunities to construct efficient multijunction tandem solar cells. However, the ion migration always causes halide segregation, which inevitably creates detrimental defects and deteriorates photovoltaic performances. Here, we report a universal caging strategy suppress segregation by in situ formation of conjugated covalent organic frameworks (COFs) catalyzed PbX2 (X = Br I) during perovskite. Through theoretical calculation systematic investigation, strong electron-donating feature COFs is shown effectively solidify soft lattice impede iodide transport from bulk grain boundary, decelerating light-induced halide-demixing process. Finally, nonradiative recombination significantly reduced, boosting efficiency up 11.50% for an inorganic CsPbIBr2 perovskite cell 14.35% CsPbI2Br with prolonged shelf life improved photostability.

Language: Английский

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Machine-Learned Kohn–Sham Hamiltonian Mapping for Nonadiabatic Molecular Dynamics

Journal of Chemical Theory and Computation, Journal Year: 2024, Volume and Issue: 20(8), P. 2992 - 3007

Published: April 6, 2024

In this work, we report a simple, efficient, and scalable machine-learning (ML) approach for mapping non-self-consistent Kohn-Sham Hamiltonians constructed with one kind of density functional to the nearly self-consistent another functional. This is designed as fast surrogate Hamiltonian calculator use in long nonadiabatic dynamics simulations large atomistic systems. approach, input output features are matrices computed from different levels theory. We demonstrate that developed ML-based method (1) speeds up calculations by several orders magnitude, (2) conceptually simpler than alternative ML approaches, (3) applicable systems sizes can be used arbitrary functionals, (4) requires modest training data, learns fast, generates molecular orbitals their energies accuracy matching conventional calculations, (5) when applied simulation excitation energy relaxation yields corresponding time scales within margin error calculations. Using explore C

Language: Английский

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