We investigated the effect of electron injection layer on the performance of organic light emitting devices (OLEDs). As an electron injection layer, the quinolate metal complexes were used. We optimized the device efficiency by varying the thickness of the quinolate metal complexes layer. The device with 1 nm of the quinolate metal complexes layer showed significant enhancement of the device performance and device lifetime. We also compared the effect of 8-hydroxyquinolinolatolithium (Liq) with that of bis(8-quinolinolato)-zinc (Znq2) and 8-hydroxyquinolinolatosodium (Naq) as an electron injection layer. As a result, Liq is considered as a better materials for the electron injection layer than Znq2 and Naq.

Recently, the phosphorescent organic light-emitting devices (OLEDs) have been extensively studied for their high internal quantum efficiency. In this study, we synthesised several phosphorescent metal complexes, and certified their composition using NMR. We also investigated the characteristics of the phosphorescent OLEDs with the green emitting phosphor, Ir(ppy)3. The devices with a structure of indium-tin-oxide(ITO)/N,N'-diphenyl-N,N'-(3-methylphenyI-1,1'-biphenyl-4,4'-diamine (TPD)/metal complex doped in host materials/2,9-dimethyl-4,7-diphenyl-l,10-phenanthroline(BCP)/tris (8-hydroxyquinolinato) Aluminum(Alq3)/Li:Al/Al was fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of tris(2-phenylpyridine)iridium (Ir(ppy)3), we fabricated several devices and investigated their characteristics.

Organic semiconductors based on vacuum-deposited films of fused-ring polycyclic aromatic hydrocarbon have great potential to be utilized as an active layer for electronic and optoelectronic devices. In this study, pentacene thin films and electrode materials were deposited by Organic Molecular Beam Deposition (OMBD) and vacuum evaporation respectively. For the gate dielectric layer, photoacryl (OPTMER PC403 from JSR Co.) was spin-coated and cured at 220℃. Electrical characteristics of the device were investigated, where the channel length and width was 50 μm and 5 mm. It was found that field effect mobility was 0.039 cm2V-1s-1, threshold voltage was -8 V, and on/off current ratio was 106. Further details will be discussed.

By fabricating the organic light-emitting devices (OLEDs) based on phosphorescent material, the internal quantum efficiency can reach 100%, compared to 25% in the case of the fluorescent material. Thus, the phosphorescent OLEDs have recently been extensively studied and showed higher internal quantum efficiencies then the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs, with the green emitting phosphor, Ir(ppy)3, (tris(2-phenylpyridine)iridium). The devices with a structure of ITO/TPD/Ir(ppy)3 doped in the host material /BCP/Alq3/Li:Al/Al were fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of Ir(ppy)3, we fabricated several devices and investigated the device characteristics. OLEDs doped into BCP by 10% showed the best characteristics. For 10% doped OLEDs, the maximum luminance of was over 10000 cd/m2, and the maximum power efficiency was 7.14 lm/W.

The effect of a-sexithiophene(α-6T) layers on the light emitting diode (LED) were studied. The α-6T was used for a buffer layer in electroluminescent (EL) devices. Enhanced carrier (hole) injection and improved emission efficiency were observed. Carrier injection characteristics were investigated as a function of α-6T later thickness. The efficiency of the electroluminescence was proportional to the thickness of α-6T layer. The highest efficiency was observed 600A of α-6T later, which was about 1.5 times higher than that of device without α-6T later. The device with a-6T showed an operation voltage lowered by 2V. The α-6T layer can substitute hole blocking layer, and control charge injection properties.

Organic Electroluminescent devices(OELD) consisted of multilayer structures have been studied for the application the application to flat-panel display. Metal-chelate complexes, zinc bis(2-(2-hydroxyphenyl)benzoxazolate) (Zn(BOX)2) and zinc bis(2-(2-hydroxyphenyl)benzothiazolate) (Zn(BOX)2), have been intensively investigated as an white-light emitting layer and recognized to have good electroluminescent(EL) properties. In this study, (Zn(BOX)2) and (Zn(BTZ)2) were synthesized and characterized by FT-IR, 1H-NMR, UV-VIS and PL. Their EL properties were also studied and their ionization potential(IP) and electron affinity(EA) were also measured by cyclic voltammetry(CV).

A water-soluble conducting polymer (CPP400 Paste) containing a derivative of polythiophene with several dopant was investigated as an anode material for organic electroluminescent devices. The device of ITO/CPP 400 Paste/TPD/Alq3/Li:Al was fabricated, where CPP 400 Paste films were prepared by spin coating and TPD and Alq3, films were prepared by vacuum evaporation. It was found that the turn-on voltage, current density, and luminance of the devices were dependent upon the thickness of CPP 400 Paste film in the Electroluminescent and current-voltage characteristics of the devices. This phenomena were explained by the energy level diagram of the device with the energy levels of the CPP400 Paste obtained by cyclic voltammetric method.

Organic semiconductors based on conjugated thiophene oligomer have great potential to be utilized as an active layer for electronic and optoelectronic devices. In this study, a conjugated oligomer such as α-sexithiophene (α-6T) thin films was prepared by the Organic Molecular Beam Deposition (OMBD), and various electrode materials were also deposited by a simple vacuum evaporation, respectively. Those films were photolithographically patterned for the electrical measurements. Electrical charact-erization of the thin film transistor with various channel length were executed and the field effect mobility of these thin film transistors were also calculated by the formula using the experimental data.

본 연구에서는 SOI 구조를 이용한 50μm 두계의 규소 태양전지의 이용 가능성과 제한사항을 제시하기 위하여, interdigitated contact을 이용한 전극을 형성하도록 전지를 설계한 후 단계별 사진공정을 통해 태양전지를 제조하였다. Bonded SOI wafer를 이용하여 제조된 50μm 두께의 결정질 규소 태양전지의 효율은 전극간격이 1100μm과 base width가 35μm인 경우에서 11.5%로 가장 높은 값을 나타내었다. 또한 실험결과로부터 전면전극을 이용한 태양전지의 구조는 power loss를 최소화하는 최적의 base fraction을 적용하는 것이 필요하며, 전지의 효율은 fill factor에 강한 의존성을 나타내기 때문에 fill factor loss를 최소화하는 설계조건이 필요함을 알 수 있었다.

Recently, high luminance and efficiency were realize in organic thin film electroluminescence (EL) cells with multilayer structures including an emitting layer (EML), hole transporting layer (HTL), and an electron transporting layer (ETL). In this study, Bis(10-hydroxybenzo[h]quinolinato)beryllium (Bebq2) was synthesized. PL and EL characteristics of their thin film were investigated by fabricating the devices having a structure of ITO/PVK/Bebq2/Al, ITO/PVK dispersed with TPD/Bebq2/Al. The EL color of these device was greenish and the wavelength of their EL peaks was located, respectly, at 495nm, and 492.5nm.

In this study, a new conducting materials, namely, a Schiff base (polymeric azomethine) was synthesized from 2,6-diamino-N-docosyl pyridinium bromide and terephthalaldehyde to obtain a soluble and fusible conducting polymer. The synthesized Schiff base structure was analyzed by using UV/vis absorption spectrophotometer, FT-IR spectrometer and 1H-NMR spectrometer. It was found that the Schiff base was successfully synthesized and soluble in carbon tetrachloride(CC14), its Langmuir-Blodgett film was easily fabricated, and its surface pressure was determined to be 30mN/m for solid state by measuring π-A isotherm.

In this study, organic electroluminescent devices(OELD) with a structure of a glass substrate/ITO/TPD/Tb(ACAC)3(Phen-Cl)/Alq3/Al was fabricated by vacuum evaporation method, where Tb complex was known to have green light emitting property. Electroluminescent(EL) and I-V characteristics of this structure were investigated. This triple-layer structure shows the green EL spectrum at the wavelwngth of 546nm, which is almost the same as the PL spectrum of Pb(ACAC)3(PhenCl). It was found in current-voltage(I-V) characteristics of the devices that the operating voltage was about 12V.

Thin films of Eu(TTA)3(phen), which was known to show red-light emitting properties, were deposited under various deposition condition. The thickness, surface morphology, and photoluminescence(PL) were measured with α-step profiler, Atomic Force Microscopy(AFM), and PL measurement apparatus. It was found that the thickness of Eu(TTA)3(phen) film can be controlled precisely by adjusting the amounts of Eu(TTA)3(phen) in the boat. As the thickness of these films increases, the surface roughness also increases. A structure of Al/Eu(TTA)3(phen)(850a)/TPD(600a)/ITO was fabricated, Electroluminescence(EL) spectrum of which shows the peak at the wavelength of 618nm.

It is well known that the metallo-phthalocyanine(MPcs) are sensitive to toxic gaseous molecules such as NO2 and also chemically and thermally stable. Therefore, lots of MPcs have been studied for the potential chemical sensor for NO2 gas using quartz crystal microbalance or electrical conductivity. In this study, 2,3,9,10,16,17,23,24-[octa-(dodecyloxy)] copper phthalocyanine and 2,3,9,10,16,17,23,24-[octa-(octyloxy)] copper phthalocyanine were synthesized and their possibility of LB film preparation were tested. It was confirmed by using FT-IR, DSC, NMR, UV-Vis absorption spectroscopy and Elemental Analysis that CuPc derivatives were successfully synthesized. From the π-A characteristics and limiting areas of two CuPc derivatives it was found that the preparation of LB films with these CuPc derivatives is possible.

In this study, MEH-PPV was synthesized and MEH-PPV and its mixtures with PMMA were deposited on substrates with Langmuir-Blodgett(LB) technique and their photoluminescent char acteristics were investigated using UV-Vis absorption spectroscopy, and photoluminescence(PL) measurements. The surface morphology of the LB films of MEH-PPV and its mixture with PMMA were investigated using Atomic Force Microscopy(AFM). Electroluminescent devices using LB films were fabricated with Al and ITO as a top and bottom electrode, respectively, and their I-V characteristics were investigated.

Tris(8-hydroxyquinoline)-aluminum complex(AlQ3) having greenish luminescent characteristics was synthesized and it was confirmed with UV-Vis absorption spectroscopy, elemental analysis, and FT-IR spectroscopy that AlQ3 was successfully synthesized. Thin films of AlQ3 having multilayer structure were prepared by spin coating method and vacuum evaporation technique. Photopluminescent characteristics of these films were investigated by Luminescence spectroscopy and Current-Voltage(I-V) characteristics of these films were also investigated.

Ultra-thin films of poly[2-[4-(9-(10-phenyl)anthracenyl)phenoxy)hexyloxy]]-1,4-phenylenevinyleylene(PAHPV) were prepare-d on the hydrophilic ITO substrate by Langmuir-Blodgett(LB) technique. λmax in the photoluminescence spectrum of these films was 458nm at the excitation wavelength of 365nm before thermal treatment, which comes from diphenylanthracene side chain of PAHPV. It was also confirmed with UV-Vis spectrometer that ultra-thin LB films of PAHPV precursor polymer were prepared well. After thermal treatment for conjugation of PAHPV precursor polymer, λmax in the photoluminescence spectrum of these films changed to 365nm, which means that the conjugation of these PAHPV films was completed.

It is well known that the metallo- phthalocyanine (MPcs) are sensitive to toxic gaseous molecules such as NO2 and also chemically and thermally stable, Therefore, lots of MPcs have been studied for the potential chemical sensor for NO2 gas using quartz crystal microbalance(QCM) or electrical conductivity. In this study, ultra-thin films of octa(2-ethylhexyloxy)copper-phthalocyanine were prepared by Langmuir-Blodgett method and characterized by using UV-VIS absortion spectroscopy and ellipsometry. Transfer condition, and characterization of LB films were investigated and preliminary results of current-voltage(I-V) characteristics of these films exposed to NO2 gas as a function of film thickness and temperature were discussed.

비정질 실리콘박막의 고상결정화 특성에 대한 비정질 박막의 증착방법, 수소화 정도, 표면결정 활성화 에너지 변화 및 열처리 환경 영향을 X선 회절, EDAX, Raman 분광 분석으로 조사하였다. 저온(580˚C)열처리 corning 시료에서 기판 barium(Ba), aluminum(AI) 성분의 막내 확산 임계열처리시간 및 확산에 기인 한 불안정 결정화 특성을 관찰하였다. 화학기상증착 석영 수소화 시료에서 hard damage 기계적 활성화 효과로 얻어진 조대결정립 결정화 특성을 X선 회절의 (111) 배향 상대강도 변화로 관찰 할 수 있었으며, 이는 활성화 효과에 의한 고상 결정화 시 핵생성과 성장속도변화로 다결정 실리콘의 전기적물성 향상 가능성을 보여주었다. Soft damage, bare 활성화 처리 수소화막의 결정화는 비정질 상의 혼재, 박막 응력등의 저품위 입계특성 및 미세결정립 성장 특성으로 관찰되었으나, 활성화 전처리에 의한 저온 및 고온(875˚C)단시간(30분) 결정화는 확인 되었다. 스퍼터링 비수소화 막의 결정화는 상변태 상태의 Raman 결정피크로 분석 되었으며, 결정화 거동에 선행막의 스퍼터링 및 비수소화 영향은 활성화효과에 관계없이 불완전 저품위 결정특성으로 확인되었다. AFM 표면형상은 3차원 island 성막특성을 보여주었고 표면거칠기정도는 높은 것으로 관찰되었다.

Ultra thin films of Tetra-3-hexadecylsulphamoylcopperphthalocyanine(HDSM-CuPc) were formed on various substrates by Langmuir-Blodgett method, where HDSM-CuPc was synthesized by attaching long-chain alkylamine(hexa-decylamine) to CuPc. The reaction product was identified with FT-IR, UV-visible absorption spectroscopies, elemental analysis and thin layer chromatography. The formation of Ultrathin Langmuir-Blodgett(LB) films of HDSM-CuPc was confirmed by FT-IR and UV-visible spectroscopies. A quartz piezoelectric crystal coated with LB films of HDSM-CuPc was examined as a gas sensor for N02 gas. HDSM-CuPc LB films were transferred to a quartz crystal microbalance(QCM) in the form of Z-type multilayers. Response characteristics of film-coated QCM to NO2 gas concentrations over a range of 100~600ppm have been tested with a thickness of 5~20 layers of HDSM-CuPc. Changes in frequency by adsorption of NO2 were increased With the number of LB layers and NO2 concentration, but the response time was slow.