Synthesis of fluorescent organic nano-dots and their application as efficient color conversion layers

Abstract

Efficient conversion of light from short wavelengths to longer wavelengths using color conversion layers (CCLs) underpins the successful operation of numerous contemporary display and lighting technologies. Inorganic quantum dots, based on CdSe or InP, for example, have received much attention in this context, however, suffer from instability and toxic cadmium or phosphine chemistry. Organic nanoparticles (NPs), though less often studied, are capable of very competitive performance, including outstanding stability and water-processability. Surfactants, which are critical in stabilizing many types of nano-structures, have not yet been used extensively in organic NPs. Here we show the utility of surfactants in the synthesis and processing of organic NPs by thoroughly characterizing the effect of ionic and non-ionic surfactants on the properties of fluorescent organic NPs. Using this information, we identify surfactant processing conditions that result in nearly 100 % conversion of organic fluorophores into sub-micrometer particles, or nano-dots, with outstanding performance as CCLs. Such water dispersions are environmentally benign and efficiently convert light. They can be used for a range of fluorophores covering a full spectral gamut, with excellent color purity, including full-width at half-maximum (FWHM) values as low as 21 nm. Compared to inorganic (InP) reference CCLs, the organic nano-dot based CCLs show superior color conversion efficiency and substantially improved long-term stability.

Carbon Dots for Electroluminescent Light‐Emitting Diodes: Recent Progress and Future Prospects

“…In phosphor-converted WLEDs, there are two general strategies to realize WLEDs. [126][127][128][129] The first strategy to generate white light emission is the combination of a blue GaN LED chip and synthesized CDs with yellow or orange emission that partially absorb blue EL from the LED chip. Although the operational process is simple, WLEDs always show a low CRI due to incomplete spectral coverage in the whole visible region, especially in the cyan and red emission regions.…”

Intriguing Role of Weak Electron Donor in Dictating the Luminescent Characteristics of DS‐A‐DW Materials

“…The figure shows that the large‐sized emission spots were formed with 90% f w , while small spots were observed with M1 in THF, validating the aggregate type formation in the former conditions. [ 51 ] These observations reveal that in the aggregated state, such as neat film conditions, the emitters will possess a higher probability of stronger intermolecular interactions that stabilize only the CT‐type excited state, resulting in LW emission characteristics. On the other hand, the stronger intermolecular interaction will gradually decrease by reducing the emitter concentration and becoming minimal at 1% dispersed condition, which allows the additional π→π* localized excited state contribution resulting in dual‐emission characteristics.…”

Montmorillonite K10 catalyzed facile synthesis of N-substituted indoles from primary amines and Morita–Baylis–Hillman acetate of cyclohexenone

“…Next, we were intrigued by the possibility of whether alkylamine could be employed in this methodology to give N -alkylindole, which is normally generated via the substitution of alkyl halide with N -free indole promoted by a stoichiometric amount of strong bases such as sodium hydride and potassium tert -butoxide. 18 To our delight, benzylamine delivered N -benzylindole 3y in 65% yield under the same conditions except for an increased reaction temperature. Then, the scope of alkylamine was contemplated.…”