Metal halide perovskites are promising candidates for use in light emitting diodes (LEDs), due to their potential for color tunable and high luminescence efficiency. While recent advances in perovskite-based light emitting diodes have resulted in external quantum efficiencies exceeding 12.4% for the green emitters, and infrared emitters based on 3 D/2D mixed dimensional perovskites have exceeded 20%, the external quantum efficiencies of the red and blue emitters still lag behind. A critical issue to date is creating highly emissive and stable perovskite emitters with the desirable emission band gap to achieve full-color displays and white LEDs. Herein, we report the preparation and characterization of a highly luminescent and stable suspension of cubic-shaped methylammonium lead triiodide (CHNHPbI) perovskite nanocrystals, where we synthesize the nanocrystals via a ligand-assisted reprecipitation technique, using an acetonitrile/methylamine compound solvent system to solvate the ions and toluene as the antisolvent to induce crystallization. Through tuning the ratio of the ligands, the ligand to toluene ratio, and the temperature of the toluene, we obtain a solution of CHNHPbI nanocrystals with a photoluminescence quantum yield exceeding 93% and tunable emission between 660 and 705 nm. We also achieved red emission at 635 nm by blending the nanocrystals with bromide salt and obtained perovskite-based light emitting diodes with maximum electroluminescent external quantum efficiency of 2.75%.
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http://dx.doi.org/10.1021/jacs.8b09706 | DOI Listing |
Sci Rep
January 2025
Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore, 632014, Tamil Nadu, India.
This study investigates the potential of zinc oxide (ZnO) and Ag-doped zinc oxide (Ag-ZnO) nanoparticles (NPs) (1, 3 and 5 wt%) electrospun into poly(vinylidene fluoride) (PVDF) based triboelectric nanogenerators (TENGs) to harness electrical energy from ambient mechanical vibrations. ZnO and Ag-ZnO NPs were developed using a co-precipitation method. 3 wt% Ag-ZnO doping was optimized to exhibit a higher β-crystalline phase in PVDF (PAZ3).
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University, Yingbin Road No.688, Jinhua, 321004, P. R. China.
Polycyclic multiple resonance (MR) molecules reveal narrowband emission, making them very promising emitters for high color purity display. Nevertheless, they still have challenges such as aggregation-induced emission quenching and spectral broadening. Overcoming these obstacles requires an in-depth understanding of the correlations among the alterations in their geometries, packing structures, and molecular vibrations and their corresponding changes in their photoluminescence (PL) properties.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Shenzhen University, College of Materials Science and Engineering, Xueyuan Avenue, 518000, Shenzhen, CHINA.
The development of pure-green organic emitters with ideal emission peak and ultra-narrow full-widths at half-maximum (FWHMs) remains a formidable challenge. Herein, we report two new green emitters, CNBN and MCNBN, which achieve extremely narrow FWHMs by synergistic rigid π-extension and cyano-substitution for sky-blue multi-resonance thermally activated delayed fluorescence (MR-TADF) core. The introduction of cyano groups induces red-shifts of emission to green region and dramatically minimize the FWHMs.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Institute of Chemistry Chinese Academy of Sciences, CAS Key Laboratory of Molecular Recognition and Function, CHINA.
A pair of axially chiral thermally activated delayed fluorescent (TADF) enantiomers, R-TCBN-ImEtPF6 and S-TCBN-ImEtPF6, with intrinsic ionic characteristics were efficiently synthesized by introducing imidazolium hexafluorophosphate to chiral TADF unit. The TADF imidazolium salts exhibited a high photoluminescence quantum yield (PLQY) of up to 92%, a small singlet-triplet energy gap (∆EST) of 0.04 eV, as well as reversible redox properties.
View Article and Find Full Text PDFNanoscale
January 2025
Department of Photonics and Institute of Electro-Optical Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.
Electroluminescent (EL) devices consisting of a single metal-semiconductor contact and a gate effect structure have garnered significant attention in the field of perovskite light-emitting devices. This interest is largely due to the thermal stability of the active layer and the simplicity of the device structure. However, the application of these devices in large-area light-emitting applications is hindered by the inherently low carrier mobility in perovskite materials.
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