Perylene Diimide as the Black-Layer Material of the OLEDs
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0965-S01-12
Perylene Diimide as the Black-Layer Material of the OLEDs Jiun-Haw Lee1,2, Kai-Hsiang Chuang1, Yu-Hsuan Ho1, Chi-Feng Lin1, Chun-Chieh Chao3, ManKit Leung3,4, Cheng-Yu Li5, and Hsuen-Li Chen5 1 Graduate Institute of Electro-Optical Engineering, National Taiwan Univ., 1, Sec. 4 Roosevelt Rd., Taipei, 10617, Taiwan 2 Department of Electrical Engineering, National Taiwan Univ., 1, Sec. 4, Roosevelt Rd., Taipei, 10617, Taiwan 3 Department of Chemistry, National Taiwan Univ., 1, Sec. 4 Roosevelt Rd., Taipei, 10617, Taiwan 4 Institute of Polymer Science and Engineering, National Taiwan Univ., 1, Sec. 4, Roosevelt Rd., Taipei, 10617, Taiwan 5 Department of Materials Science & Engineerin, National Taiwan Univ., 1, Sec. 4 Roosevelt Rd., Taipei, 10617, Taiwan
ABSTRACT In this paper, we use a perylene diimide derivative serving as a destructive and an absorption layer of the “black cathode” of an organic light-emitting device (OLED). A thin and semitransparent metal between the electron transport layer and the perylene diimide is used for better electron injection and also serves as the destructive interference. The thickness of such layer is critical since thinner metal results in lower reflectance, but higher diving voltage due to worse electron injection. To enhance the electron injection capability, the thickness of the thin metal increases which in turns to increase the reflectance. Here, we used a double-metal configuration to decrease the reflectance and maintain the electron injection capability at the same time. INTRODUCTION Organic light-emitting device (OLED) has attracted lots of attention due to the advantages of self-emissive, fast response, low driving voltage, and wide viewangle [1,2]. In a conventional OLED, a high reflectance cathode was typically used to reflect the spontaneous emission towards the cathode and couple the photons out of the device. However, for the display applications, the cathode reflection of the ambient deteriorates the contrast ratio under high illumination which limits its outdoor applications. To decrease the ambient reflection, a circular polarizer film attached on the OLED is commonly used. However, it adds extra cost and fabrication complexity in the devices. The black cathode concept was then proposed to decrease the reflectance from the cathode [3]. Typically, such a black cathode can be fabricated by using an absorbing layer, a destructive interference layer [4,5]. The criteria of this inserting layer include: (1) high conductivity for better electronic properties, (2) high thermal stability for longer lifetime. If this layer is absorptive, the absorption coefficient of the material should be as large as possible and the absorption spectrum of the material should cover the whole visible range. Black cathode OLED with destructive interference is to replace the conventional cathode of OLED
with a stack of “thin metal-organic electron transport layer-thick metal” cathode (the so-called MOM structure cathode). In this MOM structure cathode, the reflection light from t
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