The carriers’ transportation between layers of two-dimensional (2D) perovskites is inhibited by dielectric confinement. Here, for the first time, we employ a femtosecond laser to introduce ultrafast shock pressure in the range of 0~15.45 GPa to reduce dielectric confinement by modulating the structure and exciton dynamics in a perovskite single crystal (PSCs), e.g. (F-PEA)2PbI4 (4-fluorophenethylammonium, F-PEA). The density functional theory (DFT) simulation and experimental results show that the inorganic framework distortion results in a bandgap reduction. It was found that the exciton-optical phonon coupling and free excitons (FEs) binding energy are minimized at 2.75 GPa shock pressure due to a reduction in dielectric confinement. The stability testing under various harsh light and humid thermal conditions shows that femtosecond laser shocking improves the stability of (F-PEA)2PbI4 PSCs. Femtosecond laser shock processing provides a new approach for regulating the structure and enhancing halide perovskite properties.

transport dynamics, which is the key for high-performance perovskite devices. At present, precursor solution additive as a convenient and effective method has been widely used in the structural optimization of perovskite films, [8] such as doping in the perovskite lattice to form bonds, [9] and additives to form hydrogen bonds with perovskites. [10] Quantum dots (QDs) are often doped in perovskite grain boundaries to reduce the boundary barrier for promoting the transport of photogenic carriers. [11] In addition, additives to prevent water/oxygen penetration by forming strong chemical bonds at the interface are important way to improve the stability of perovskite films. [12] Although precursor solution additive method provides an excellent material based for the structural optimization, the current postprocessing methods are limited to fabricate crystalline perovskite films to control their structure and properties, due to the challenges in manipulate the heating/cooling rate, residual stress, and microstructure, such as grain size, intragrain defects, and grain boundary defects. Laser has been widely used in semiconductor processing because of its advantages of monochromatism, coherence, directionality, high speed processing, scalability, wide range control of energy density, and wavelength. The laser-assisted processing technology was developed for rapid processing of perovskite, [13] which can facilitate the postprocessing of perovskite devices with high speed. Moreover, compared with the traditional thermal annealing, the energy consumption of laser treatment is much less. [14] In addition, The temperature control at the material interface, such as grain boundaries, is critical for defect density, and phases, which are important for high-performance perovskite-based optoelectronic devices. However, it is challenging to fine-tune the microstructures in perovskite films with well-controlled grain structure, interface defects, porosity, phase structure, and strains, simultaneously. Here, pulsed laser technology is combined with carbon quantum dots (CQDs) into perovskite absorbers with pore-free, less defect, high crystallinity, enhanced absorption, low stress, and phase-stabilized microstructures. Due to laser-CQD interaction-induced grain boundary microstructure changes, perovskite films can be fabricated with much larger grains (>10 times) than those after thermal annealing. As CQDs are embedded to passivate grain, this leads to reduced grain boundary barrier at the interface, which significantly improve the carrier transportation in perovskite films. The shift of perovskite band to vacuum energy level leads to remarkable improvement of carrier extraction efficiency and lifetime, leading to much higher mobility of photogenerated carriers and diffusion length (>1 μm). The laser-induced thermomechanical momentum significantly enhances crystal interface with hydrophobic perovskite film, resulting in much less residual tensile stress by 20 times and excellent stability. Pulsed-laser-assisted QD additive engineerin...

Nanosecond laser shock annealing is used to induce ultrafast organic salt diffusion into the PbI2 layer to modulate the crystalline structure, residual tensile strain, and electron transport kinetics of perovskite films.

The orientation of crystals on the substrate and the presence of defects are critical factors in electro‐optic performance. However, technical approaches to guide the orientational crystallization of electro‐optical thin films remains challenging. This article reports on a novel physical method called magnetic field assisted pulse laser annealing (MAPLA) for controlling the orientation of perovskite crystals on substrates. By inducing laser recrystallization of perovskite crystals under a magnetic field and with magnetic nanoparticles, the optical and magnetic fields w ere found to guide the orientational gathering of perovskite units into nanoclusters, resulting in perovskite crystals with preferred lattice orientation in (110) and (220) perpendicular to the substrate. The perovskite crystals obtained by MAPLA exhibited significantly larger grain size and fewer defects compared to those from pulsed laser annealing (PLA) and traditional thermal annealing, resulting in improved carrier lifetime and mobility. Furthermore, MAPLA demonstrated improved device performance, increasing responsivity and detectivity by two times, and photocurrent by nearly three orders compared with PLA. The introduction of Fe2O3 nanoparticles during MAPLA not only improved crystal size and orientation but also significantly enhanced long‐term stability by preventing Pb2+ reduction. The MAPLA method has great potential for fabricating many electro‐optical thin films with desired device properties and stability.This article is protected by copyright. All rights reserved