자외선-C 발광 YPO4:Pr3+ 분말제조 및 YPO4:Pr3+-PVDF 전계 발광소자 특성 연구

정용석,백경도,아판디 모하메드,박재홍,김종수 한국반도체디스플레이기술학회 2022 반도체디스플레이기술학회지 Vol.21 No.2

The ultraviolet-C emitting praseodymium doped yttrium phosphate (YPO4:Pr3+) powder was synthesized by conventional solid-state reaction. The electroluminescence device was fabricated by simple screen-printing method using the synthesized YPO4:Pr3+ powder, especially, polyvinylidene fluoride as an insulating layer was applied on the printed YPO4:Pr3+ powder for stable performance of the electroluminescence. The electroluminescence properties were investigated under alternating current power system of 400 Hz. The device starts to emit at 350 V, which showed the ultraviolet-C emission peaking at the 233, 245, 264, 273 nm attributed to electronic transition of the Pr3+ ions. The electroluminescence intensity was increased as increasing the operating voltage and the device revealed stable performance up to 600 V due to the polyvinylidene fluoride serve as a protective layer.

Phenothiazine derivatives as an easily accessible emitter for green light-emitting electrochemical cells

Jongseong, Kim,Shanmugasundaram, Kanagaraj,Chitumalla, Ramesh Kumar,Jang, Joonkyung,Choe, Youngson Elsevier 2018 Journal of luminescence Vol.197 No.-

<P><B>Abstract</B></P> <P>A new phenothiazine derivatives of an ionic small molecules were synthesized and its photo- and electrochemical properties were evaluated. The compounds NPzN and PPzP exhibits good thermal stabilities and shows positive solvatochromism upon increasing the polarity of the solvents. The single-component electroluminescence devices were fabricated from solution by incorporating both the emitters. Light-emitting electrochemical cell devices exhibited green color electroluminescence for both the compounds with the CIE coordinates of (0.28, 0.43) and (0.32, 0.41). These results indicate that phenothiazine derivatives have a promising prospect in the application of solution processed green LECs.</P> <P><B>Graphical abstract</B></P> <P>Light-emitting electrochemical cells based phenothiazine derivatives were fabricated. Devices exhibited green electroluminescence.</P> <P>[DISPLAY OMISSION]</P>

양자점 층의 미세구조 형상이 양자점 LED 전계 발광 특성에 미치는 효과

윤성룡,전민현,이전국,Yoon, Sung-Lyong,Jeon, Minhyon,Lee, Jeon-Kook 한국재료학회 2013 한국재료학회지 Vol.23 No.8

Quantum dots(QDs) with their tunable luminescence properties are uniquely suited for use as lumophores in light emitting device. We investigate the microstructural effect on the electroluminescence(EL). Here we report the use of inorganic semiconductors as robust charge transport layers, and demonstrate devices with light emission. We chose mechanically smooth and compositionally amorphous films to prevent electrical shorts. We grew semiconducting oxide films with low free-carrier concentrations to minimize quenching of the QD EL. The hole transport layer(HTL) and electron transport layer(ETL) were chosen to have carrier concentrations and energy-band offsets similar to the QDs so that electron and hole injection into the QD layer was balanced. For the ETL and the HTL, we selected a 40-nm-thick $ZnSnO_x$ with a resistivity of $10{\Omega}{\cdot}cm$, which show bright and uniform emission at a 10 V applied bias. Light emitting uniformity was improved by reducing the rpm of QD spin coating.At a QD concentration of 15.0 mg/mL, we observed bright and uniform electroluminescence at a 12 V applied bias. The significant decrease in QD luminescence can be attributed to the non-uniform QD layers. This suggests that we should control the interface between QD layers and charge transport layers to improve the electroluminescence.

LDPE의 전하이동과 전계발광 현상

조재철,최용성,문성창,황종선,이경섭 대한전기학회 2008 전기학회논문지 P Vol.57 No.3

Polymers submitted to thermo/electrical stress suffer from ageing that can drastically affect their functional behaviour. Understanding the physico/chemical processes at play during ageing and defining transport regimes in which these mechanisms start to be critical is therefore a prime goal to prevent degradation and to develop new formulation or new materials with improved properties. It is thought that a way to define these critical regimes is to investigate under which conditions (in terms of stress parameters) light is generated in the material by electroluminescence (EL). This can happen through impact excitation/ionization involving hot carriers or upon bi-polar charge recombination (a definition that excludes light from partial discharges, which would sign an advanced stage in the degradation process). After a brief review of the EL phenomenology under DC, we introduce a numerical model of charge transport postulating a recombination controlled electroluminescence. The model output is critically evaluated with special emphasize on the comparison between simulated and experimental light emission. Finally, we comment some open questions and perspectives.

Application of Excited-State Intramolecular Proton Transfer (ESIPT) Principle to Functional Polymeric Materials

Park, Sang-Hyuk,Kim, Se-Hoon,Seo, Jang-Won,Park, Soo-Young The Polymer Society of Korea 2008 Macromolecular Research Vol.16 No.5

Synthesis and properties of novel excited-state intramolecular proton transfer (ESIPT) materials, recently developed in our group, are described. Highly efficient ESIPT reaction, achieved in polyquinolines, polybenzoxazoles, and oxadiazole and imidazole derivatives possessing an intramolecular tautomerizable hydrogen bond, has been investigated theoretically and experimentally. It is demonstrated that unique properties arising from the ESIPT process (large Stokes' shift, no self-absorption, and easy population inversion, etc.) make it possible to produce advanced polymer devices for lasing, optical storage, and electroluminescence.

Red Electroluminescence Device Using a Cu-Coated CaS:Eu2+ Phosphor

Jun-Seok Park,최진철,최진문,Boo-Won Park,김종수 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1

Cu-coated CaS:Eu2+ phosphors are synthesized by using a wet-processing method. The alternat- ing current(A.C.) powder electroluminescence devices are fabricated by a screen-printing method: ITO PET lm/phosphor layer (Cu-coated CaS:Eu2+)/dielectric layer (BaTiO3)/silver electrode. Their electroluminescence spectra show a deep red emission peaking at 650 nm due to the f-d tran- sitions of Eu2+ ions in CaS:Eu2+ phosphor, indicating that the purity of red color is superior to that with a commercial ZnS:Mn2+ phosphor. With increasing Cu concentration, the electroluminescent intensity is maximized at an optimal Cu concentration and then decreases, which is explained by two competing factors, an improved conductivity and a reduced transparency. Cu-coated CaS:Eu2+ phosphors are synthesized by using a wet-processing method. The alternat- ing current(A.C.) powder electroluminescence devices are fabricated by a screen-printing method: ITO PET lm/phosphor layer (Cu-coated CaS:Eu2+)/dielectric layer (BaTiO3)/silver electrode. Their electroluminescence spectra show a deep red emission peaking at 650 nm due to the f-d tran- sitions of Eu2+ ions in CaS:Eu2+ phosphor, indicating that the purity of red color is superior to that with a commercial ZnS:Mn2+ phosphor. With increasing Cu concentration, the electroluminescent intensity is maximized at an optimal Cu concentration and then decreases, which is explained by two competing factors, an improved conductivity and a reduced transparency.

Quantum Efficiency in Multi-quantum well InGaN/GaN Light-emitting Diodes with Electroluminescence Characteristics

Ok Hwan Cha,Cheol-Hoi Kim,Jun Seok Lee,Jong Pil Jeong,Joong Seo Park,Jandi Kim,정현,Eun-Kyung Suh 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1

The temperature dependence of the electroluminescence spectra of InGaN/GaN multi-quantumwell light-emitting diodes (LEDs) has been investigated over a range of temperatures and currents. The presence of localization effects in the active InGaN layers can be deduced from the observed considerable blue shifts of the electroluminescence emission peak with increasing temperature in the low-temperature region. Exciton-phonon couplings in the active layer are also observed at low temperatures. The electroluminescence intensity was measured to determine the internal quantum efficiency of the LEDs as a function of temperature. When the temperature decreases from room temperature to 170~200 K, the electroluminescence intensity increases due to a reduction in the nonradiative recombination, and the internal quantum efficiency is improved. At T < 170 K, the electroluminescence intensity is reduced significantly. This reduction of the electroluminescence intensity mainly results from the low carrier capture efficiency in the active layer due to the high Mg activation energy, the electron-hole separation in multi quantum wells, and the high internal piezoelectric field. However, in the case of LEDs using a narrow barrier, the electroluminescence intensity is reduced slightly at low temperatures. Therefore, in order to measure the internal quantum efficiency by using the temperature dependence of the electroluminescence spectra in LEDs, one must carefully consider the effects of carrier injection at low temperature.

Y2SiO5:Eu3+ 형광체 기반 적색 전계 발광 소자

허훈,정현지,박순호,김종수 한국반도체디스플레이기술학회 2023 반도체디스플레이기술학회지 Vol.22 No.1

Y2SiO5 Powder based on silicon and yttrium is well known as powder phosphors due to their excellent sustainability and efficiency. A new electroluminescence device was fabricated with Y2SiO5:Eu3+ powder phosphors though a simple screen printing method. The powder-dispersed electroluminescence device consisted of the Y2SiO5:Eu3+ powder-dispersed phosphor layer and BaTiO3-dispersed dielectric layer. The annealing temperature of the phosphor for the best powder electroluminescence performance was optimized to high temperature in ambient atmosphere though a solid-state reaction. The Eu3+ concentration for the best device performance was also investigated and furthermore, the thermal dependence of the electroluminescence intensity was investigated at the operating voltage of 100℃ which is the Curie temperature of the BaTiO3 layer. And the intensity was exponentially increased with voltage and was linearly increased with frequency.

New Conjugated Polymer Based on Dihydroindoloindole for LEDs

Jin, Yeong-Eup,Kim, Kwang-hyun,Song, Su-hee,Kim, Jin-woo,Kim, Jae-hong,Park, Sung-Heum,Lee, Kwang-hee,Suh, Hong-suk Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.7

New electroluminescence polymer, poly(5,10-dihexyl-5,10-dihydroindolo[3,2-b]indole-2,7-diyl) (PININO) was synthesized by Yamamoto conditions with Ni(0) catalyst. The full characterization of structures and properties as well as the performances of the electroluminescence devices of the new polymer are presented. The resulting polymer, which exhibits good solubility in common organic solvents, was used as the electroluminescence layer for the light-emitting diodes (LEDs) (ITO/PEDOT/polymer/Al). PININO shows turn-on voltage of 2.5 V, and electroluminescence (EL) with maximum peak at 490 nm, maximum brightness of 40 cd/$m^{2}$ at 8 V, and efficiency of 0.002 cd/A at 350 mA/$cm^{2}$.

투명한 교류 분말형 전계발광 소자 특성 연구

김대한,박재형,장원태,박광원,강태욱,권성열 한국화상학회 2016 한국화상학회지 Vol.22 No.2

투명한 교류 분말형 전계발광 소자는 Electroluminescence (EL) 용 ZnS계 형광체와 시아노 에틸 유기바인더의 첨가량을 달리하여 제작하였다. 전면전극 indium thin oxide(ITO) glass 위에 약 3 μm 크기 의 형광체로 발광층을 형성하여 silver nanowire(Ag NW)를 스핀코팅으로 후면전극 형성 후 연구를 진행 하였다. 본 연구에 제작된 소자의 발광휘도와 투과도을 통해 등황색 계열의 약 585 nm의 주파장 스펙트 럼을 확인하였고 형광체의 첨가량이 낮아질수록 발광휘도가 약 80 %로 감소, 투과도는 약 30 % 증가하 는 것을 알 수 있었다. Transparent A.C Powder electroluminescence device based on ZnS : Cu, Mn phosphor mixed cyan oethycellulose of weight ratio. 3μm size phosphor based on device consist of a ITO glass/Phosphor layer/Ag NW electrode by spin coating. Transparent electroluminescence device showed the yellow-orange luminescence peak. Varying phosphor weight ratio, We confirmed according to phosphor quantity, if it diminish, decrease electroluminescence about 80%, transmittance increase about 30%