Sharif Digital Repository

In this work, a simple method to prepare white light emissive diodes based on quantum dot (QD) colloidal solutions using mixed carbon QDs (CQDs) and CsPbI3 perovskite (PQDs) is reported. The right combination generates emission across the entire visible spectrum upon ultraviolet excitation. The white light emission of the final films provides high and stable color rendering index of 92%, tuning the chromaticity coordinates of the emission through the applied voltage. By varying the CsPbI3 QD concentration, a mixture is obtained that emits the “warm”, “neutral”, and “cold” white light sought for many indoor lighting applications, or to approximate the visible region of the solar spectrum,... 

In this work, a GaN-based quantum well LED is theoretically analyzed in a multi-layer structure composed of a quantum well embedded in a waveguide core surrounded by photonic crystal slab and a sapphire substrate. The electromagnetic eigenmodes are obtained throughout above structure via revised plane wave-scattering matrix method. The omnidirectional transmission and reflection are investigated for both TE and TM polarizations from diffraction channels in Ewald construction. Then, we introduced angular power density and calculated radiative modes extraction efficiency. All structural parameters, such as lattice geometry, lattice constant, photonic crystal thickness and filling factor, are... 

A novel binary BiOI/ZnFe2O4 (BZ) with p-n heterojunction based on the different metal-organic framework (MOF) MIL-88B(Fe) and graphite carbon nitride (g-C3N4) as substrates has been designed. As-prepared ternary nanocomposites have been first obtained via a simple hydrothermal system and subsequently deposited onto the MOF and g-C3N4 substrates. The photoactivity of the ternary nanocomposites was evaluated by organic pollutants degradation under LED light. These characterization results indicated that BiOI as a p-type semiconductor was well deposited on the surface of ZnFe2O4 (n-type semiconductors). The p-n heterojunction photocatalyst (BZ) improved the valence band potential of ZnFe2O4 and... 

In this work, a simple method to prepare white light emissive diodes based on quantum dot (QD) colloidal solutions using mixed carbon QDs (CQDs) and CsPbI3 perovskite (PQDs) is reported. The right combination generates emission across the entire visible spectrum upon ultraviolet excitation. The white light emission of the final films provides high and stable color rendering index of 92%, tuning the chromaticity coordinates of the emission through the applied voltage. By varying the CsPbI3 QD concentration, a mixture is obtained that emits the “warm”, “neutral”, and “cold” white light sought for many indoor lighting applications, or to approximate the visible region of the solar spectrum,... 

In this study, we designed, engineered and investigated two new thermally activated delayed fluorescence (TADF) dyes obtained from D–A–D′ type, consisted of 2-(9H-carbazol-9-yl)-3-(3-methoxy-9H-carbazol-9-yl)-9H-xanthen and 2-(3,6-di-tert-butyl-9H-carbazol-9-yl)-3-(3-methoxy -9H-carbazol-9-yl)-9H-xanthen. In these dyes, xanthen derivative and carbazole derivatives have played important roles as an acceptor and two unsymmetrical donor units. In addition, the photophysical properties of these dyes were evaluated by the UV–VIS absorption, photoluminescence spectroscopy and photoluminescence decay lifetime analysis in solution, initial dye, non-doped and doped solid state (neat–film) at... 

Transition metal oxides are being more frequently used as hole injection layer (HIL) in organic light emitting diodes (OLEDs), in place of polymer HILs such as PEDOT:PSS. The very thin films of the metal oxide HILs are usually deposited using vapor deposition, in order to create uniform films. Here, we report OLEDs fabricated using solution processed MoOx films as the HIL and super yellow as the emissive layer. The performance of the devices is comparable to PEDOT:PSS based devices, while the stability tests show the lifetime of MoOx-based devices is 4 × 106 h, about 40 times longer than PEDOT:PSS devices, at typical working condition. X-ray photoelectron spectroscopy (XPS) indicates both...