Owing to the enlarged exciton binding energy and the ability to confine charge carriers compared to their three-dimensional (3D) counterparts, research on quasi-two-dimensional (quasi-2D) perovskite materials and the correlative application in light-emitting diodes (LEDs) has attracted considerable attention. However, high density of defects, exciton emission trapping, and unbalanced charge injection are still the main intractable obstacles to their further development and practical application. Herein, we report an efficient multifunctional interlayer, lithium fluoride (LiF), to boost the performance of green-emitting quasi-2D perovskite LEDs (PeLEDs) by simultaneously overcoming the aforementioned issues. The introduced LiF interlayer not only eliminates the defects at perovskite grain boundaries and the surface by reinforcing the chemical bonds with uncoordinated lead ions but also restrains the emission of perovskite from quenching triggered by the electron transport layer and reduces excess electron injections to effectively balance carriers in the device. As a result, the resulting green quasi-2D PeLED shows a maximum external quantum efficiency of 16.35%, which is the best value obtained for quasi-2D perovskite-based LEDs reported so far, with simultaneous improvement in the operating lifetime of the device.
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http://dx.doi.org/10.1021/acsami.0c11762 | DOI Listing |
Adv Mater
January 2025
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, China.
Formamidinium lead iodide (FAPbI) perovskite films, ensuring optically active phase purity with uniform crystal orientation, are ideal for photovoltaic applications. However, the optically active α-FAPbI phase is easy to degrade into δ-phase due to numerous defects within randomly oriented films. Here, a "quasi-2D" perovskite template is pre-deposited on the film surface within the crystallization process based on the two-step preparation technology, which directly induced pure and highly orientated crystallization of α-FAPbI across the downward growth process.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Physics, SUNY University at Buffalo, Buffalo, NY, 14220, USA.
Quasi-2D perovskite made with organic spacers co-crystallized with inorganic cesium lead bromide inorganics is demonstrated for near unity photoluminescence quantum yield at room temperature. However, light emitting diodes made with quasi-2D perovskites rapidly degrade which remains a major bottleneck in this field. In this work, It is shown that the bright emission originates from finely tuned multi-component 2D nano-crystalline phases that are thermodynamically unstable.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, China.
Quasi-two-dimensional (quasi-2D) mixed-halide perovskites are a requisite for their applications in highly efficient blue perovskite light-emitting diodes (PeLEDs) owing to their strong quantum confinement effect and high exciton binding energy. The pace of quasi-2D blue PeLEDs is hindered primarily by two factors: challenges in precisely managing the phase distribution and defect-mediated nonradiative recombination losses. Herein, we utilize 2,2-diphenylethylamine (DPEA) with bulky steric hindrance to disturb the assembly process of a slender spacer host cation, 4-fluorophenylethylammonium (-F-PEA), enhancing phase distribution management in quasi-2D PeLEDs.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
Hebei Key Laboratory of Photo-Electricity Information and Materials, College of Physics Science and Technology, Hebei University, Baoding, 071002, P. R. China.
Metal halide perovskites (MHPs) are commonly used in polarization-sensitive photodetectors (PDs) for applications such as polarization imaging, remote sensing, and optical communication. Although various methods exist to adjust the polarization-sensitive photocurrent, a universal and effective approach for continuous control of MHPs' optoelectronic and polarized properties is lacking. A universal strategy to electrically modulate the polarization ratio (PR) of self-powered polarized PDs using the ferro-pyro-phototronic effect (FPPE) in 2D perovskites is presented.
View Article and Find Full Text PDFSmall
January 2025
State Key Laboratory of Crystal Materials, Shandong University, 27th South Shanda Road, Jinan, 250100, China.
The demand for medical imaging with reduced patient dosage and higher resolution is growing, driving the need for advanced X-ray detection technologies. This paper proposes a design paradigm for X-ray detection semiconductors by coupling constituent motifs through crystal structure engineering. The study introduces a strongly anisotropic Aurivillius-type quasi-2D perovskite structure, combining [BiO] groups with stereochemically active lone pair electrons (SCALPEs) and [W/MoO] anionic groups, enabling enhanced X-ray Compton scattering and self-powered capabilities through local electric field ordering.
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