In the present study, pyrolyzed fuel oil (PFO)-based pitch without impurities was used to prepare coke under pressure, and the preparation yield and the powder resistance depending on the graphitization were investigated. The preparation yield of green coke by pressurized coking at 500 °C was about 26–27% higher than that at normal pressure. However, the coke yield after the thermal treatment of green coke at 900 °C was lower by 10.6–14.8% at the pressurization conditions than under normal pressure. This may be because the substances that are not vaporized under the pressurized conditions remain in the reactants and then are discharged later. The coke yield after the thermal treatment at 900 °C was higher by 14.9–28.3% under the pressurized conditions than under the normal pressure, indicating that the low-boiling point materials of the pitch participated more in coke polymerization under the pressurized conditions. The density of the coke prepared under the pressurized conditions was lower than that of the coke prepared under normal pressure, because the low-boiling point materials of the pitch participated in the reaction. However, after graphitization, the density values became similar (2.27–2.26 g/cm3). The volume resistivity of the graphitized samples was in a range of 0.499 × 10–2–0.384 × 10–2 Ω cm, indicating that the coke samples have similar electrical properties. The results of the present study show that, in comparison with the conventional normal-pressure process, the pressurized coking process can improve the yield through the participation of low-boiling point materials in the polymerization reaction, while maintaining the properties of the prepared coke and graphite, such as the conductivity and density.

The carbon anode material for lithium-ion battery was prepared by pyrolysis fuel oil and waste polyethylene terephthalate (PET) additive. The pitch was synthesized as a medium material for carbon anode by heat treatment. The waste PET additive improved the softening point and thermal stability of the pitch. La and Lc of the anode material (heat-treated pitch) increased at higher treatment temperature but decreased by waste PET additive. The electric capacity was evaluated based on effects of defective cavity and developed graphite interlayer, respectively. When the La and Lc of the anode material decreased, the electric capacity by cavity increased based on defective graphite structure. Therefore, the addition of waste PET causes the improved capacity by the cavity. The anode material which has a high efficiency (over 95%) and C-rate (95%, 2 C/0.1 C) was obtained by controlling the process of heat treatment and PET addition. The mechanism of lithium-ion insertion was discussed based on effects of defective cavity and developed graphite interlayer.

The mesophase pith was synthesized based on effects of a high-pressure thermal condensation and feed (PFO/FCC-DO) blending. The reaction conditions were designed by fluidity and reactivity of each feed during the thermal reaction. The high-pressure thermal condensation process disturbs distillation of the volatile compounds in pyrolysis fuel oil (PFO); the fluidity can be controlled. In the blending process, PFO, which has a high thermal condensation reactivity, and fluid catalytic cracking-decant oil (FCC-DO), which maintains fluidity, interacted with a synergistic effect. Thus, mesophase pitch with a large mesophase content was manufactured by the two above processes.

This research considers the effect of added mesophase pitch (MP) as an additive during the pitch synthesis reaction of pyrolyzed fuel oil (PFO). Two effects are generated by adding MP. One is an enhancement of thermal stability due to the high thermal property of the additive; the other is that the volatile compounds that were removed by vaporization of PFO during the thermal reaction can participate in the pitch synthesis reaction (PFO→pitch) more efficiently. The effect differs according to the amount of the additive. When the amount of the additive is less than 7 wt%, the first effect is dominant, whereas the second effect is dominant when the additive amount exceeds 10 wt%.

분산된 유전입자를 가지는 OLED는 입자의 표면 상태에 의하여 새로운 부가적인 결과를 나타내게 된다. 본 논문에서는 유전입자가 분산된 Polyfluorene (PFO) 발광 층과 두 개의 전극을 가지는 간단한 구조의 PFO-base OLED를 제작하고 분산된 나노입자들이 분산을 위한 제작공정에서 필수적으로 발생하는 표면상태변화가 소자에 어떠한 영향을 미치는지 알아보았다. Spin-coating 공법으로 제작된 PFO-base OLED는 극소량 첨가된 유전입자의 고른 분산을 위한 공정이 필요하며 이 공정으로 인해 입자의 표면에서 scratch 가 증가 하고 , 또한 입자의 분쇄가 이루어 지기도 한다. 교반 시간의 증가는 표면 scratch와 입자의 분쇄를 증가시키게 되고, 이는 입자크기의 감소와 분쇄된 입 자끼리의 응집을 증가시켜 소자의 electrical conditioning을 변화시켰고 나아가 발광 특성에 영향을 주었다. 실험 결과 9시간 정도의 교반시간에서 입자의 표면전하로 인해 electrical conditioning이 개선되고 이로서 소자의 발광휘도가 최대 2.5배 이상 증가하였다. 반면에 교반시간이 증가하면 소자의 전반적인 휘도는 다소 감소하는 결과를 나타내었다. 이는 표면전하 증가와 함께 분산이 고르게 되지 않기 때문인 것으로 생각된다.

Polyfluorene (PFO) 발광 층과 두 개의 전극으로 이루어진 단순한 구조의 PFO polymer base OLED를 기본으로 강유전성의 BaTiO₃나노입자를 PFO 발광 층 내에 분산시킨 OLED 소자를 제작하여 분산된 강유전체 나노입자의 영향과 동작에 미치는 역할을 알아보았다. 140 nm 두께의 발광 층 내부에 대비 80 nm의 크기를 가지는 강유전성 BaTiO₃입자들은 OLED 동작 중에 인가전압에 의해 대전되어 전기쌍극자를 형성하고, PFO의 발광 층 내로 주입된 전자 및 정공들과 각각 coulomb force에 기인하는 상호작용을 하여 OLED 소자의 전류밀도가 증가하는 결과를 나타내었다. PFO의 질량대비 10 wt% 에 해당하는 소량을 첨가하였을 때에 OLED소자의 문턱전압이 약 2 V 감소하는 개선된 결과를 나타내었다. 또한 유전체가 첨가되지 않은 소자에 비하여 휘도가 약 2 배 증가한 결과를 나타내었다.

전도성 고분자 PFO(Polyfluorene)에 양전극 ITO와 음전극으로 AI 를 추가한 단순한 양극성 구조의 ITO/PFO/Al 소자를 제작하였다. PFO에 BaTIO₃나노세라믹스 분말을 중량비로 0wt%, 10wt%, 20wt% 와 30wt% 로 달리한 4종류의 시편에 만들고, Keithley 사의 2400 Sourcemeter를 이용하여 0V에서 21V까지 DC전압을 인가하면서 소자에 흐르는 전류량을 관찰하였다. 수 나노 크기의 BaTIO₃분말의 첨가는 PFO/AI 계면에서의 전위장벽을 감소시켜 Fowler-Nordheim Tunneling이 시작되는 전압이 BaTIO₃가 첨가되지 않은 시편의 경우에 비하여 7V에서 최대 10V가 낮아진 결과를 얻었다. 소자에 흐르는 최대 전류값은 인가 전압 DC21V일 때 BaTIO₃첨가량에 비례하여 4배에서 5.5배까지 증가하였다. BaTIO₃의 첨가효과는 20wt% 이상 첨가된 경우 효과가 포화되기 시작하여, 30wt%의 BaTIO₃를 첨가한 시편의 전류량은 오히려 감소하였고 전류주입도 어려워지는 상반된 결과를 얻었다. 이것은 첨가한 나노 분말의 표면전하가 만드는 미세전계의 영향이 인접한 거리에서 서로 중첩되어 전류의 흐름이 오히려 감소하는 결과를 보인 것을 판단된다. 이로서 강유전체가 첨가된 전도성 고분자/금속 계면의 I-V 특성은 나노 세라믹스 분말의 표면전하가 만드는 국소미세전계의 영향을 받아 Trap Charge Limited Current 모델에 부합하는 결과를 가짐을 알 수 있었다.

Polymer Light Emitting Diodes (PLEDs) with an ITO/PEDOT:PSS/PVK/PFO-poss/LiF/Al structure were prepared on plasma-treated ITO/glass substrates using spin-coating and thermal evaporation methods. The annealing effects of the PFO-poss film when it acts as the emission layer were investigated by using electrical and optical property measurements. The annealing conditions of the PFO-poss emission film were 100 and 200˚C for 1, 2 and 3 hours, respectively. The luminance increased and the turn-on voltage decreased when the annealing temperature and treatment time increased. After examining the Luminance-Voltage (L-V) properties of the PLED, the maximum luminance was found to be 1497 cd/m2 at 11 V for the device when it was annealed at 200˚C for 3 hours. The peak intensity of the PLED emission spectra at approximately 525 nm in wavelength increased when the annealing temperature and time of the PFO-poss film increased. These results suggest that the light emission color shifted from blue to green.