垂直式有機電晶體驅動有機發光二極體之整合製程研發

Abstract

未來顯示技術的主流，主動式有機發光顯示器（AMOLED），具有高解析度、高反 應速度以及輕薄的優勢，因此成為大家紛紛研究的目標。一般都是使用無機或是有機蒸鍍製程的電晶體作為背板，製成開關和驅動電晶體後，再在相同的基板上進行有機發光二極體（OLED）的製程。本論中，研發整合以垂直式有機電晶體驅動OLED 的新製程技術，分別在兩個基板上，利用刮刀技術的溶液製程製成 space-charge-limited transistor(SCLT) 和有機小分子發光二極體兩個元件，之後利用一般用於封裝的導電錫球，以150°C 的熱風加熱5 分鐘，垂直地將兩個元件焊接接合，其中錫球直徑為40 μm，接合後接觸電阻為10 Ω。而此製程前，為了使電晶體達熱穩定的狀態，所以也將電晶體以150 °C加熱5 分鐘，讓輸出電流密度達25 mA/cm2，並且確定錫球焊接製程不會對SCLT 和OLED 產生影響。如此製程整合的元件，在總偏壓8 V 下，SCLT 操作開關，將下發光的白光有機小分子發光二極體亮度由308 mA/cm2 到關閉；將橘光有機發光二極體由亮度603 mA/cm2 到關。新研發的製程技術具有不受開口率限制和低成本的有機溶液製程 等的優勢。本論文的另外一部分，關於軟性電子元件的研究，已研發出以可撓性的不鏽鋼為基板，製成主動區面積1 mm2 的SCLT 元件，並且具有電晶體開關比104 的特性。而在可撓性基板彎曲的情況下，電晶體有仍保有了開關的操作能力，未來除了可以與發光顯示器作結合，也可以應用在電子紙等軟性基板的結合上。

Active-matrix organic light-emitting diode (AMOLED) is an emerging technology for display. A variety of vacuum-processed transistor backplanes are used for the pixel driving circuit of AMOLED. The OLED and the transistor are usually fabricated on the same glass substrates. We research the new integrated processes for driving transistor. The vertical organic space-charge-limited transistor (SCLT) made of P3HT and small-molecule phosphorescent organic light-emitting diode (OLED) are made on two separate glass substrate by blade coating, then soldered vertically together by tin balls with 40 μm diameter. The soldering is done by hot wind of 150 °C for 5 minutes. Contact resistance is only 10 Ω. Before soldering, the SCLT is post-annealed to reach a stable characteristic and enhance the output current up to 25 mA/cm2. Both OLED and the annealed vertical transistor are not affected by the soldering process. The vertical transistor has 1/4 of the OLED area and turns on the bottom-emission white OLED up to 300 cd/m2 and orange OLED up to 600 cd/m2. The entire operation is within 8 V. This new integrated processes has the advantages of no limit by aperture ratio and solution process. Then, the other new process about flexible displays. We research fabrication of the SCLT on flexible stainless steel substrate. The Stainless steel thickness is 75 μm. The SCLT can be bent to a radius of 1 cm and have the switching performance.