• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.69-72
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• 2021

Various studies for QLEDs using inkjet printing has been actively conducted. Multilayers in QLEDs need an orthogonal process inevitably using different solvents and it makes the inkjet printing process more difficult and expensive. Therefore, coating two layers in a single process can reduce the fabrication step, resulting in the process time. In this study, we fabricated QLEDs of standard structure using a mixture of emission layer and hole transport layer. The mixed layer was fabricated by dissolving TFB and QDs in chlorobenzene, and the maximum luminance of the device was 45,850 cd/m². It shows the bright future of the electroluminescence devices applied with inkjet printing process.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.355-356
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• 2006

The glass transition behavior of OLED materials is very important for both processing and lifetime. We report about the correlation between the structure of selected small molecule Hole Transport Materials (HTM's) and their glass transition temperature. The thermal stability of devices manufactured with them was investigated. The results give researchers and engineers some information which are helpful for designing new molecules and processing them in device making.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.147.3-147
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• 1998

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.3
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• pp.151-155
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• 2014

We have developed quantum dot light emitting diodes (QD-LEDs) using a InP/ZnSe/ZnS multi-shell QD emission layer. The hybrid structure of organic hole transport layer/QD/organic electron transport layer was used for fabricating QD-LEDs. Poly(4-butylphenyl-diphenyl-amine) (poly-TPD) and tris[2,4,6-trimethyl-3-(pyridin-3-yl)phenyl]borane (3TPYMB) molecules were used as hole-transporting and electron-transporting layers, respectively. The emission, current efficiency, and driving characteristics of QD-LEDs with 50, 65 nm thick 3TPYMB layers were investigated. The QD-LED with a 50 nm thick 3TPYMB layer exhibited a maximum current efficiency of 1.3 cd/A.

• Ceramist
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• v.23 no.2
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• pp.145-165
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• 2020

Halide perovskites are promising photovoltaic materials due to their excellent optoelectronic properties like high absorption coefficient, low exciton binding energy and long diffusion length, and single-junction solar cells consisting of them have shown a high certified efficiency of 25.2%. Despite of high efficiency, perovskite photovoltaics show poor stability under actual operational condition, which is the mostly critical obstacle for commercialization. Given that the stability of the perovskite devices is significantly affected by charge-transporting layers, the use of inorganic charge-transporting layers with better intrinsic stability than the organic counterparts must be beneficial to the enhanced device reliability. In this review article, we summarized a number of studies on the inorganic charge-transporting layers of the perovskite solar cells, especially focusing on their effects on the enhanced device reliability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.497-500
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• 2001

Due to their better photosensitivity in X-ray, the amorphous selenium based photoreceptor is widely used on the X-ray conversion materials. It was possible to control the charge carrier transport of amorphous selenium by suitably alloying a-Se with other elements(e,g. As, Cl). The charge transport properties of amorphous Selenium is decided on hole which is induced from metal to selenium in metal-selenium junction and which is transferred in a-Se bulk. This phenomenon is resulted of changing electric field owing to increasing of space charge by deep trap of a-Se bulk. In this paper, We dopped the chlorine to compensate deep hole trap and deposited blocking layer using dielectric material to prevent from increasing space charge for injection charge between metal electrode and a-Se layer. We compared space charge and the decreasing of trap density through measuring dark and photo current.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.1
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• pp.74-80
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• 2009

In the structure of ITO/N,N'-diphenyl-N,N' bis (3-methylphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris (8-hydroxyquinoline)aluminum($Alq_3$)/Al device, we studied the efficiency improvement of organic light-emitting diodes due to variation of deposition rate of hole transport layer (TPD) materials using hole-size of crucible boat. The thickness of TPD and $Alq_3$ was manufactured 40 nm, 60 nm, respectively under a base pressure of $5{\times}10^{-6}$ Torr using a thermal evaporation. The $Alq_3$ used for an electron-transport and emissive layer were evaporated to be at a deposition rate of $2.5\;{\AA}/s$. When the deposition rate of TPD increased from 1.5 to $3.0\;{\AA}/s$, we studied the efficiency improvement of TPD using the hole-size of crucible is 1.0 mm. When the deposition rate of TPD is $2.5\;{\AA}/s$, we found that the average roughness is rather smoother, the luminous efficiency the external quantum efficiency is superior to the others. Compared to the two from the devices made with the deposition rate of TPD is $2.0\;{\AA}/s$ and $3.0\;{\AA}/s$, the external quantum efficiency was improved by four-times and two-times, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.963-965
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• 2003

We have synthesized new hole transport materials(HTMs). Then we have fabricated structures of ITO/new HTM/$Alq_{3}$/EIL/Al. New HTM based devices have higher current density and lower turn-on voltage than TPD based devices. New HTMs have higher HOMO level than TPD. The new HTM based OLEDs have shown better current injection than the TPD based OLEDs, due to the lower injection barrier between ITO surface and HTM.

• Transactions on Electrical and Electronic Materials
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• v.6 no.6
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• pp.280-283
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• 2005

The moving photocarrier grating (MPG) technique for the determination of the carrier mobilities and the recombination lifetime of $\alpha$-Se:As films has been studied. The electron and hole drift mobility and the recombination lifetime of $\alpha$-Se films with arsenic (As) additions have been obtained from measurement of the short circuit current density $j_{sc}$ as a function of grating velocity and spatial period. The hole mobility decreases due to defect density of hole traps when x exceeds 0.003, whereas the hole mobility increases for the case of low As addition (x$\le$0.003). We have found an increase in hole drift mobility and recombination lifetime, especially when As with (x = 0.003) is added into the $\alpha$-Se film.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.147.4-147
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• 1998