Inorganic single crystals with anisotropic structures usually suffer from high brittleness and stiffness. Flexible polymers are used to replace inorganic crystals, but the hot-stretching-induced orientation process is tedious, and oriented molecular chains tend to revert to random coils during aging. To overcome these obstacles and using the similarities between sub-1 nm nanowires (NWs) and linear polymers, we successfully fabricated anisotropic, transparent, flexible, and stable (ATFS) NW films with great potential for optical applications through a wet-spinning method. The NW films show birefringence, and their birefractive index is higher than that of many polymers. They also showed polarized absorption of UV light and anisotropic scattering of visible light. The integrated films composed of NWs and quantum dots showed good fluorescence polarization. The tedious synthesis of quantum rods and fabrication of oriented polymer films can thus be avoided.
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http://dx.doi.org/10.1002/anie.201902240 | DOI Listing |
When exposed to light, the colloidal perovskite nanoplatelets (NPLs) in the film can fuse into larger grains, and this phenomenon was thought to be closely related to ion migration. However, the available CsPbBr NPLs are not conducive to directly distinguishing this hypothesis. Herein, we prepare mixed-halide perovskite CsPbBrI NPLs by a ligand-assisted reprecipitation method and investigate the photoluminescence evolution of NPLs under laser irradiation.
View Article and Find Full Text PDFJ Chem Phys
October 2024
Laboratório de Espectroscopia Óptica e Fotônica, Universidade Federal de Alfenas, 37715-400 Poços de Caldas, Minas Gerais, Brazil.
A theoretical-experimental approach is proposed to convert the photoluminescence spectra of colloidal perovskite quantum dot ensembles into accurate estimates for their intrinsic particle size distribution functions. Two main problems were addressed and properly correlated: the size dependence of the first excitonic transition in a single cube-shaped quantum dot and the inhomogeneous broadening of the fluorescence line shape due to the size nonuniformity of the chemically prepared quantum dot suspension in addition to the single-dot homogeneous broadening. By applying the reported methodology to CsPbBr3 quantum dot samples belonging to the strong and intermediate confinement regimes, the calculated size distributions exhibited close agreement with those obtained from transmission electron microscopy, with precise estimates for the average particle size and standard deviation.
View Article and Find Full Text PDFSmall
December 2024
Key Laboratory for Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710062, P. R. China.
High-quality CsPbI with low defect density is indispensable for acquiring excellent photoelectric performance. Meticulous regulation of the CsPbI crystal growth processes is both feasible and efficacious in enhancing the quality of perovskite films. In this study, the cesium formate (CsFo) is introduced.
View Article and Find Full Text PDFAdv Mater
November 2024
Department of Energy Science, Center for Artificial Atoms, Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do, 16419, Republic of Korea.
Colloidal quantum dot (QD)-based light-emitting diodes (QD-LEDs) have reached the pinnacle of quantum efficiency and are now being actively developed for next-generation displays and brighter light sources. Previous research has suggested utilizing inorganic hole-transport layers (HTLs) to explore brighter and more stable QD-LEDs. However, the performance metrics of such QD-LEDs with inorganic HTLs generally lag behind those of organic-inorganic hybrid QD-LEDs employing organic HTLs.
View Article and Find Full Text PDFACS Nano
August 2024
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
Inorganic colloidal cesium lead halide perovskite nanocrystals (NCs) encapsulated by surface capping ligands exhibit tremendous potential in optoelectronic applications, with their surface structure playing a pivotal role in enhancing their photophysical properties. Soy lecithin, a tightly binding zwitterionic surface-capping ligand, has recently facilitated the high-yield synthesis of stable ultraconcentrated and ultradilute colloids of CsPbX NCs, unlocking a myriad of potential device applications. However, the atomic-level understanding of the ligand-terminated surface structure remains uncertain.
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