Metal sacrificial-layer-assisted transfer is a promising strategy for transferring thermally annealed thin films onto flexible polymer substrates without exposing the receiver substrate to thermal damage. However, stable release of the annealed thin-film stack remains challenging because high-temperature annealing can alter the etching behavior of the sacrificial metal layer and the protective oxide layer. In this study, we propose a thin-film transfer process using a Ni metal sacrificial layer and etch access holes, in which an SU-8/Ti/SiO2 transferable stack was fabricated on a rigid sapphire donor substrate, annealed at 400–700°C, selectively released by Ni etching, and transferred onto a flexible PET receiver substrate. As the annealing temperature increased from 400 to 700°C, the SiO2 etch rate decreased from 6.8–6.96 to 2.61–3.83 nm/s, while the Ni release time increased from 72–77 to 82–95 min; nevertheless, the transferable stack was successfully transferred under all process conditions with image-based transfer yields of 58.81–82.76%, with the highest yield obtained for the 200 nm Ni sacrificial layer annealed at 550°C. These results demonstrate the process feasibility of the proposed metal sacrificial-layer and etch-access-hole-based transfer approach for transferring thermally annealed thin-film structures from rigid donor substrates to flexible receiver substrates.
Perovskite light-emitting diodes (PELEDs) are emerging as promising candidates for next-generation displays, thanks to their narrow full width at half maximum and low-cost solution processing capabilities. Blue PeLEDs are essential for achieving a full-color gamut; however, efficiency and stability challenges limit their practical use. A primary bottleneck arises from interfacial issues between the perovskite emissive and charge transport layers. This review summarizes the key interfacial challenges hindering the performance of blue PeLEDs and highlights recent advances in interfacial engineering strategies. By focusing on interfacial engineering between the hole-transport layer and perovskite, this review compares different strategies and outlines future directions for developing high-performance blue light-emitting devices.
Beom Jin Kim, Pil Hong Jeong, Jae Min Lee, Dong Hwan Won, Jeong Ho Lee, Heon Min Lee, Ku Yun Jeong, Keon Park, Kawan Anil, Soon Jae Yu, Yeon Sik Chae, Sung Bae Park
J Korean Inst Electr Electron Mater Eng 2025;38(3):272-277. Published online May 1, 2025
SMD-type 660 nm wavelength semiconductor laser diode device is fabricated using silicon resin molding technology and fabricated a BT resin printed circuit board. BT resin electrode structure printed circuit boards with soldering electrode pads and through holes for heat dissipation were fabricated. The SMD process is an injection molding technique in which the chip is molded from silicon material and then cut by a dicing process to complete the beam emission surface. The fabricated SMD-type semiconductor laser diode exhibits a good near-field beam pattern with no scattering/dispersion caused by the printed circuit board or silicon molding in the emitted laser beam, or reflections around the chip. It was also confirmed that the heat generated at 20 mA operation has good heat dissipation characteristics through the through-hole heat dissipation structure.
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Mitigating Contact‐Constricted Thermal Bottlenecks by Magnetically Programmable hBN Bridge Fillers in Al2O3/Epoxy Composites Yeonwook Jeong, Sabina Ghorsaine, Chan‐Jae Lee, In Kim, Mooho Lee, Hyejeong Lee, Ginam Kim, Jong‐Woong Kim Small.2026;[Epub] CrossRef
This review examines the use of halide perovskite materials in electronic devices, highlighting their exceptional optoelectronic properties and the challenges associated with them. Despite their potential for high-performance devices, practical applications are limited by sensitivity to environmental factors such as moisture and oxygen, etc. We discuss advances in enhancing stability and operational reliability, featuring innovative synthesis methods and device engineering strategies that help mitigate degradation. Furthermore, we explore the integration of perovskites in applications such as field-effect transistors and LEDs, emphasizing their transformative potential. This review also outlines future research directions, stressing the need for ongoing improvements in material stability and device integration to fully realize the commercial potential of perovskites.
We have developed inverted green phosphorescent organic light emitting diodes (OLEDs) using 1,1-bis[(di-4- tolylamino)phenyl]cyclohexane (TAPC) and bis(carbazole-9-yl)biphenyl (CBP) hole transport layers. The driving voltage, current efficiency, power efficiency, and emission characteristics of devices were investigated. While the driving voltage for the same current density was about 1~2 V lower in the devices with the TAPC layer, the maximum luminance was higher in the device with the CBP layer. The maximum current efficiency and power efficiency were 3.2 and 2.7 times higher in the device with the CBP layer, respectively. The higher efficiency in the CBP device resulted from the enhanced hole-electron balance although weak parasitic recombination takes place in the CBP hole transport layer.
The development of efficient electron donor (or hole-transporting) molecules that can be used in various optoelectronic device fields is highly demanded. In this work, a novel class of triptycene-based three-dimensional (3D) triphenylamine (TI-TPA) derivatives with different end substituents was designed and prepared for transparent electron donor materials. Owing to the rigid 3D triptycene framework, the obtained TI-TPA derivatives had an amorphous morphology with high thermal decomposition temperature. The oxidation potential of these TI-TPA derivatives decreased as the electron donating strength of the end substituent increased. Among TI-TPA derivatives, TI-TPA-OMe exhibited the highest HOMO level (-5.31 eV) which is similar to that of Spiro-OMeTAD (-5.22 eV). In addition, TI-TPA-OMe was found to form a strong charge transfer complex with the triptycene-based acceptor TI-BQ, leading to a new absorption band at around 640 nm. These results can be applied for developing efficient electron donor materials that can mimic the advantages of the spiro-linked structure and TPA units of Spiro-OMeTAD.
Inorganic-organic hybrid perovskite solar cells have demonstrated a significant achievement by reaching a certified power conversion efficiency of 25.2% in 2019 as compared to that of 3.8% in 2009. However, organic hole conductors such as PTAA and spiro-OMeTAD are known to be expensive and unstable when they are exposed to operational conditions. In this study, the inorganic hole conductor CuSCN was used to overcome such concerns. The influence of dipropyl sulfide (DPS) and diethyl sulfide (DES) as CuSCN deposition solvents on the underlying perovskite active layer was investigated. DES solvent was observed to be advantageous in terms of CuSCN solubility and mild for the perovskite layer, thereby resulting in a power conversion efficiency of 16.9%.
A poly[bis(4-butypheny)-bis(phenyl)benzidine] (poly-TPD) and poly(9-vinylcarbazole) (PVK) bilayer was employed as a hole transport layer (HTL) in solution-processed CdSe/ZnS quantum dot light-emitting diodes (QLEDs). The thickness of the PVK layer spin-coated onto the poly-TPD layer, whose thickness was fixed to 40 nm, was varied, with PVK layer thicknesses of 0 nm, 35 nm, 45 nm, and 55 nm. Because the thickness of the PVK can determine the hole transport properties of the HTL, a PVK thickness that maximizes the performance of the HTL for the QLEDs was investigated. By employing the optimized PVK thickness of 45 nm, the current efficiency of the QLED exhibited a 1.74 times improvement when compared with that of the QLED with poly-TPD based HTL without PVK. This was mainly attributed to the decrease in the energy barrier between the HTL and the quantum dot (QD) emitting layer (EML).
In this study, we investigated plasmon effects to maximize the sterilization of dielectric discharge. We predicted the effect using the finite difference time domain (FDTD) method as a function of electrode shape, size, and period. The structure of the electrode was designed with a thickness of 100 nm of silver nanoparticles on a glass substrate, and was varied according to the shape, size, and period of the electrode hole. Based on the results, it was confirmed that the effect of plasmons was independent of the shape of the electrode hole. It was thus confirmed that the plasmon effect depended only on the size and period of the holes. Further, the plasmon effect was affected by the size rather than period of the holes. Because the absorption of light by the metal varied according to the size of the hole, the plasmon effect generated by the absorption of light also varied. The best results were obtained when the radius and period of the electrode holes were 0.1 μm and 0.4 μm, respectively.
Hydrogenated Amorphous Silicon (a-Si:H) is used as an emitter layer in HIT (heterojunction with Intrinsic Thin layer) solar cells. Its low band gap and low optical properties (low transmittance and high absorption) cause parasitic absorption on the front side of a solar cell that significantly reduces the solar cell blue response. To overcome this, research on CSC (carrier Selective Contacts) is being actively carried out to reduce carrier recombination and improve carrier transportation as a means to approach the theoretical efficiency of silicon solar cells. Among CSC materials, molybdenum oxide (MoOx) is most commonly used for the hole transport layer (HTL) of a solar cell due to its high work function and wide band gap. This paper analyzes the electrical and optical properties of MoOx thin films for use in the HTL of HIT solar cells. The optical properties of MoOx show better performance than a-Si:H and μc-SiOx:H.
We were designed the hole transport layer of the new composite skeleton structure having a high charge mobility and thermal stability. In this paper, a hole transport layer material based on thiophene molecular structure capable of hole mobility characteristics and high triplet energy was designed and synthesized. The structures and properties of the synthesized compounds were characterized by NMR, fluorescence spectroscopy and energy band gap. As a result of NMR measurement, it was confirmed that when analyzing the integrated type with the position where the measured peak is displayed, it agrees with the structure of hole transport materials. The emission characteristics of the hole transport layer material showed absorption characteristics at 412 nm and 426 nm, respectively, and exhibited emission characteristics in the range of 469 nm and 516 nm.
Hole explosion behaviors were observed during drilling fine holes with laser beam on the LTCC green bar of 320 ㎛ thick after lamination of green sheets prepared by tape casting of thick film process. The incidence of these hole explosions was inversely proportional to hole sizes. The incidence of hole explosion was 20 % number of hole with the size of 60 ㎛ exploded for the UV radiation, while the explosion did not appear for hole sizes over 100 ㎛. To prevent hole explosion behavior during laser-drilling of fine holes, carbon black powder was added as an additive in the LTCC composition, which has superior thermal durability. As a consequence, hole explosion rate was suppressed to 0.8 % for the hole size of 50 ㎛ green sheet with the carbon black amount of 10 weight % and the laser power of 3 watt. Added carbon is thought to reduce the heat-affected region during laser drilling.
A new information society of late has arrived by the rapid development of various information & communications technologies. Accordingly, mobile devices which are light and thin, easy and convenient to carry on the market. Also, the requirements for the larger television sets such as fast response speed, low-cost electric power, wider visual angle display are sufficiently satisfied. The currently most widely studied display material, the Organic Light-emitting Diodes(OLEDs) overwhelms the Liquid Crystal Display(LCD), the main occupier of the market. This new material features a response speed of more than a thousand times faster, no need of backlight, a low driving voltage, and no limit of view angle. And the OLEDs has high luminance efficiency and excellent durability and environment resistance, quite different from the inorganic LED light source. The OLEDs with simple device structure and easy produce can be manufactured in various shapes such as a point light source, a linear light source, a surface light source. This will surely dominate the market for the next generation lighting and display device. The new display utilizes not the glass substrate but the plastic one, resulting in the thin and flexible substrate that can be curved and flattened out as needed. In this paper, OLEDs device was produced by changing thickness of Teflon-AF of hole injection material layer. And as for the electrical properties, the four layer device of ITO/TPD/Alq3/BCP/LiF/Al and the five layer device of ITO/Teflon AF/TPD/Alq3/BCP/Lif/Al were studied experimentally.
We proposed and demonstrated the double layered metallic nano-hole structure using polystyrene beads process to enhance the sensitivity of surface plasmon resonance (SPR). The double layered SPR structures are calculated using the finite-difference time-domain (FDTD) method for the width, thickness, and period of the metallic nano-hole structures. The thickness of the metal film and the metallic nano-hole is 30 and 20 nm in the 214 nm wide nano-hole size, respectively. The double layered SPR structures are fabricated with monolayer polystyrene beads of 420 nm wide. The sensitivities of the conventional SPR sensor and the double layered SPR sensor are obtained to 42.2 and 52.1 degree/RIU, respectively.
In this study, we propose Ti hole pattern structure on the transparent conductive oxide (TCO) lessdye-sensitized solar cells (DSSCs) using the lift-off process to improve the low light transmittance and lowefficiency caused by opaque Ti electrode. The formation of Ti hole patterns make it possible to move the dyeadsorption and electrolyte. The DSSCs with Ti hole patterns showed a higher photoelectric conversion efficiency(PCE) than those with general structure by 11.1%. As a result, The Ti hole pattern structure can be improved toincrease the light absorption of the dyes and PCE of the TCO-less DSSCs is also increased.
Novel materials of Zn(HPB)2 and Ir-complexes were respectively synthesized as blue or redemitting material. White Organic Light Emitting Diodes (OLED) were fabricated by using Zn(HPB)2 for ablue emitting layer, Ir-complexes for a red emitting layer and Alq3 for a green emitting layer. White OLED was fabricated by using double emitting layers of Zn(HPB)2 and Alq3:Ir-complexes, and hole blocking layer of BCP. We also varied the thickness of BCP. When the thickness of BCP layer was 5nm, white emission was achieved. We obtained a maximum luminance of 3,500 cd/m2. The CIE coordinates was (0.375, 0.331). From this study, we could propose that the hybrid structure is efficient in lighting application of white OLED by improvement of color purity.
In this research, the electric characteristic of organic light-emitting diodes(OLEDs) was studied depending on thickness of amorphous fluoropolymer(Teflon-AF) which is the material of hole injection layer to improve electric characteristic of OLEDs. Sample composition was fabricated in double layer. The basic structure was fabricated by ITO/tris(8-hydroxyquinoline) aluminum (Alq3)/Al and the 2 layer was fabricated by ITO/2,2-Bistrifluoromethyl-4,5-Difluoro-1,3-Dioxole(Teflon-AF)/tris(8-hydro xyquinoline) aluminum (Alq3)/Al. The experiment was carried with variation of thickness of Teflon-AF at 1.0, 2.0, 2.5, 3.0 nm. The result showed when Teflon-AF thickness was 2.5 nm, the electric and optical characteristic were well performed. Moreover, when it was compared with Teflon-AF without materials, it was improved 15.1 times more on luminance, 12.7 times more on luminous efficiency and 12.1 times more on external quantum efficiency. Therefore, OLEDs element with optimum hole injection layer reduced energy barrier and driving voltage, and confirmed that it improved efficiency widely.
In this study, the heat transfer capability have been improved by using via-holes in FR4 PCB, when the LED lighting is designed to solve the thermal problem. The thermal resistance and junction temperature were measured by changing the dimension of FR4 PCB and size of via hole. As a result, when the dimension was increased initially, the thermal resistance and junction temperature was decreased rapidly, the ones was stabilized after the dimension of 200 [mm2]. Also, the light output was improved up to maximum 17% by formation of via-hole and expansion of dimension in FR4 PCB. Therefore, the thermal resistance and junction temperature could be improved by expansion of PCB dimension and configuration of via-hole ability.
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Reflection Characteristics of Electroplated Deposits on LED Lead frame with Plating Condition SeHo Kee, Wonjoong Kim, JaePil Jung Journal of the Microelectronics and Packaging Society.2013; 20(2): 29. CrossRef
Anisotropic Wet-Etching Process of Si Substrate for Formation of Thermal Vias in High-Power LED Packages B.K. Yu, M.Y. Kim, T.S. Oh Journal of the Microelectronics and Packaging Society.2012; 19(4): 51. CrossRef
In order to investigate the emission characteristics of the phosphorescent white organic light-emitting diodes (PHWOLEDs) according to various hole transport layers (HTLs), PHWOLEDs composed of HTLs whose structure are NPB/TCTA, NPB/mCP and NPB/TCTA/mCP, two emissive layers (EMLs) which emit two-wavelengths of light (blue and red), and electron transport layer were fabricated. The applied voltage, power efficiency, and external quantum efficiency at a current density of 1 ㎃/㎠for the fabricated PHWOLEDs were 7.5 V, 11.5 lm/W, and 15%, in case of NPB/mCP, 5 V, 14.8 lm/W, and 13.7%, in case of NPB/TCTA, and 5.5 V, 14.6 lm/W, and 15%, in case of NPB/TCTA/mCP in the hole transport layer, respectively. High emission efficiency can be obtained when the amount of hole injection from anode is balanced out by the amount of electron injection from the cathode to EML by using NPB/TCTA/mCP structured HTL.
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