Ag-Doped ZnInS/ZnS Core/Shell Quantum Dots for Display Applications

Abstract

Development of nontoxic quantum dots (QDs) exhibiting superior photoluminescence properties is a major challenge in the commercialization of QDs-based solid-state lighting or display device applications. This work reports the synthesis of heavy-metal-free Ag:Zn−In−S/ZnS (Ag:ZIS/ZS) core/shell QDs via the heating-up method followed by a nonaqueous hot-injection route. Formation of the QDs, their growth, and structural qualities were studied by high-resolution transmission electron microscopy and XRD analysis. The optical properties of these QDs were investigated through absorption, photoluminescence, and time-resolved fluorescence decay spectroscopic measurements. Surface passivation of the core Ag:ZIS QDs was done by coating ZnS layers on them. The successful doping of Ag + into the ZnInS host material changed the emission characteristics; the influence of Ag loading and the shell thickness on the optical features were studied. The shell thickness had a strong impact on the photophysics of the nanocrystal with enhanced radiative lifetime. By regulating the Ag concentration, the Ag:ZIS core QDs showed a wide ranging tunable emission from 392 to 547 nm with a prominent blue shift with the introduction of ZnS shell layers. The blue shift in the band gap energy and emission wavelength has been reported to be due to the cation-exchange process of Ag:ZIS/ZS core/shell QDs. The radiative excited state lifetime is prolonged with subsequent injection of shells with the highest reported value being 504.72 ns. These nontoxic core/shell QDs, endowed with notable spectral emission within the visible spectrum, can be used as a down-converting material by tailoring the dopant concentration and shell precursor injection. Furthermore, a nanocomposite film of PMMA−QDs was synthesized by the drop-casting method, and its overall luminous efficacy complements that of parental core/shell QDs without quenching. The transmittance plot delineates that the optical transparency of the film can be engineered over the entire visible spectrum by varying the dopant (Ag) concentration.

Exciton Dynamics in Colloidal CdS Quantum Dots with Intense and Stokes Shifted Photoluminescence in a Single Decay Channel

“…Semiconductor quantum dots (QDs) have attracted significant attention over the last few decades, due to their excellent optical properties that arise due to quantum confinement effect, − and pave the way for a myriad of potential applications. − Cadmium chalcogenide QDs constitute an important class of these materials, with facile size, shape, and capping group-dependent wavelength tunability of emission across the visible region of the spectrum. ,− Besides, high photoluminescence quantum yields (PLQYs) and ease of chemical processability makes this particular class of QDs attractive. ,,− Optical amplification and lasing, demonstrated in these materials, − form one class of potential applications. Competition from efficient nonradiative processes of Auger recombination (AR) and surface trapping are important issues that need to be addressed in this context. , While surface trapping can be reduced effectively by growing a passivating shell of a higher band gap material around the emitting dot, AR poses a more formidable challenge.…”

Effect of Mn2+ Doping on the Photoluminescence of Hybrid One-Dimensional Lead Halide Post-Perovskites

“…Three-dimensional (3D) lead halide materials (APbX 3 , A = Cs + , methylammonium; X = Cl, Br, I) have emerged as unique optoelectronic materials that have various applications in solar cells, photodetectors, light-emitting diodes (LEDs), solid-state lasers, thermochromic materials, and many smart sensor devices. − Due to their better charge carrier mobilities, optimizable band gap nature, high photoluminescence quantum yield (PLQY), entire spectrum range coverage, fast radiation decay, fewer midgap trap states, and lower defect tolerance capabilities, − these materials have applications in display devices and solid-state lighting . Despite these amazing advancements, 3D hybrid perovskites have faced increasing issues regarding stability against moisture, water decomposition, and temperature degradation, which hinder the use of these materials for practical applications in optoelectronics. − …”

Enhanced stability and tunable photoluminescence in Mn2+-doped one-dimensional hybrid lead halide perovskites for high-performance white light emitting diodes

“…Furthermore, 3D APbX 3 -based materials offer potential applications in solid-state lighting and display technologies, owing to their attractive optical properties, such as high PLQY, tunable bandgaps, emission wavelengths spanning the entire visible spectrum, narrow linewidths and rapid radiation decay rates. [9][10][11][12] Nonetheless, 3D perovskites have some remaining drawbacks including moisture absorption, water decomposition, and limited thermal stability, which impede their use in optoelectronics. Low-dimensional hybrid metal halide perovskites present an alternative to 3D perovskites, offering benets such as tunable emission wavelength, enhanced PLQY, improved moisture resistance, and thermal stability.…”