RESUMEN

The use of supplementary cementitious materials is customary in contemporary concretes. Different industrial by-products and waste materials have been investigated earlier for such applications. In this paper, the use of organic light-emitting diode glass (OLED) display waste as a partial replacement of cement binder in concretes has been explored. Concretes with 10%, 20%, and 30% substitution (by weight) of ordinary Portland cement (OPC) by OLED powder were developed, and the resulting mechanical properties and durability characteristics were evaluated. The results showed that OLED addition leads to strength improvement of up to 8% after 28-day age. Also, the resistance to chloride-ion penetration and sulfate attack improved considerably. The chloride binding capacity for the developed concretes was also investigated. It was demonstrated that the OLED powder incorporation is beneficial in improving the corrosion resistance of the modified concrete. The enhanced mechanical and durability properties of modified concrete point toward the excellent performance of OLED-incorporated concrete for improved service life. Incorporating OLED display waste in concrete as a partial cement replacement can also reduce environmental burden and concrete cost.

Asunto(s)

Cloruros , Corrosión , Vidrio , Halógenos , Polvos

RESUMEN

In this study, we report on the development and testing of hydrophobic coatings using cellulose fibers. The developed hydrophobic coating agent secured hydrophobic performance over 120°. In addition, a pencil hardness test, rapid chloride ion penetration test, and carbonation test were conducted, and it was confirmed that concrete durability could be improved. We believe that this study will promote the research and development of hydrophobic coatings in the future.

RESUMEN

This paper reports the numerical study on the impact of energy level variation of the hole injection layer (HIL) in the organic light emitting diodes (OLEDs). We used a thin CuPc layer for the hole injection and S-TAD (2,2',7,7'-tetrakis-(N,N- diphenylamino)-9,9-spirobifluoren) for the hole transfer layer, S-DPVBi (4,4'-bis (2,2'-diphenylvinyl) -1,1'-spirobiphenyl) for the emission layer, and Alq3 (Tris (8-hyroxyquinolinato) aluminium) for the electron transfer layer. Device B has tri-layer structure except HIL. We used three models which are four layer structures for our simulation. HIL of Device A has 5.3 eV of highest occupied molecular orbital (HOMO) level and 3.8 eV of lowest unoccupied molecular orbital (LUMO) level. Also, we varied the LUMO level and HOMO level of the thin CuPc layer, which are named as Device C and Device D, respectively. Our numerical study represented that Device D has the most amount of recombination rate due to Device D has the most carrier density in the emission layer. Device A has 4.381 x 10(25) cm(-3)s(-1) of recombination, Device B has 6.439 x 10(25) cm(-3)s(-1) of recombination and Device D has 7.499 x 10(25) cm(-3)s(-1) of recombination. Consequently, nevertheless the insertion of HIL does not always improve recombination rate and we observed the recombination rate can improve about 16% according to HOMO level of HIL.

Asunto(s)

Luz , Humanos

RESUMEN

In this paper, we report our numerical investigation on the top-emitting OLED (Organic Light Emitting Diodes) with micro-cavity. Our numerical model includes an ensemble of radiating dipole antennas for light emission as well as Poisson Equation for carrier injection and transportation. We formulated a set of differential equations by the Finite Element Method. Our simulation revealed that the recombination rate is affected by the thickness of each layer comprising the OLED structure and the amount of emission is determined by the total thickness of the OLED structure due to micro-cavity effect which is observed in between the total reflection layer and the half reflection layer. Our numerical solver enables us to optimize the OLED structure and thereby improve the external quantum efficiency.

RESUMEN

In this paper, we report a theoretical study on the electronic-optical properties of the organic light emitting diodes (OLEDs) devices having a multilayer structure which consists of N,N'- bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine (TPD) as a hole transport layer (HTL) and tris(8-hydroxyquinolinato)aluminum (Alq3) as an electron transport layer (ETL). We investigated the angular dependence of the light density of emission as well as CIE chromaticity for devices with and without a distributed Bragg reflector (DBR) between the ITO and the glass wherein the DBR comprise two species of materials with different refractive indices. Our simulation revealed that the insertion of the bottom mirror plays a critical role for the improvement of in the emission efficiency of 17% and the sharper emission characteristics. We found out that the chromaticity as well as the viewing angle improved with the presence of the bottom mirror.

RESUMEN

Top-emitting organic light-emitting diodes (OLEDs) with a microcavity structure are presented in this paper. We performed a finite element (FE) analysis of a trilayer OLED that was inserted between the reflective layer and the semi-reflective layer of a device. We carried out an optical analysis of this OLED device and calculated the optimal width between the reflective layer and the semi-reflective layer to consider the microcavity effect. Our simulation revealed that the thickness of each layer can affect the recombination rate at the emission layer. We used five OLED devices. Device A is a reference device with a 42.5 nm hole transport layer (HTL), a 15 nm emission layer (EML) and a 45 nm electron transport layer (ETL). We varied the thickness of the HTL of Device A to 20 nm and 65 nm, and designated these devices as Device B and Device C, respectively. We also varied the thickness of the ETL of Device A to 20 nm and 65 nm, and designated these devices as Device D and Device E, respectively. As the thickness of the HTL and the ETL are decreased, a higher recombination rate is achieved. However, the highest recombination rate does not necessarily correspond to the highest external quantum efficiency (EQE) owing to the resonance effect. Our simulation revealed that the overall thickness of the device seems to be a more significant factor owing to the path of light.