White LED based on polyfluorene Co-polymers blend on plastic substrate

Abstract

We report on high-performance, white light emission from polyfluorene co-polymers blend and study of the opto-electrical properties of polymer blend light-emitting devices (PLEDs) fabricated on plastic substrate. Our results show that efficient white light emission via energy transfer, producing higher device efficiencies and luminance in comparison with the conventional single PLEDs, can be realized by blending carrier donor (host) and acceptor (guest) organic polyfluorene co-polymers. A maximum luminance of 7400 cd/m 2 was achieved at 13 V with Internationale de L'Eclairage coordinates of (0.33, 0.33). Maximum emission efficiency of 2 0 cd/A and power efficiency of 1 1 lm/W are obtained for white light PLEDs on plastic substrate. Index Terms-Flexible plastic substrate, polymer blend, polymer light-emitting diodes (PLEDs), white polymer light-emitting diodes (WPLEDs). I. INTRODUCTION O VER the last several years, light-emitting devices (LEDs) based on organic materials have been attractive research subjects because of their potential applicability to large-size flat panel displays (FPDs) and solid-state lighting. The use of plastic substrates can add both device flexibility and reduced thickness, weight, and manufacturing costs of large-area FPDs [1]-[4]. Also, white light single-layer organic LEDs (OLEDs) can be used as a plane light source for current large-area liquid-crystal display (LCD) TVs and as back plane for future flexible full color displays in combination with color filters. Since the early 1990s, there have been many studies reporting the white light emission from either small moleculeor polymer-based devices. In 1995, Kido et al. developed an OLED consisting of three emitter layers with different carrier transport properties, each emitting blue, green, and red light to generate the white light [5]. In 1999, Deshpande et al. also demonstrated a white light emitting OLED consisting of green and blue emitting layers doped with a red emitting material. Here, the light emission was controlled by varying the concentration of the doping material and the thickness of Manuscript

Novel Current-Scaling Current-Mirror Hydrogenated Amorphous Silicon Thin-Film Transistor Pixel Electrode Circuit with Cascade Capacitor for Active-Matrix Organic Light-Emitting Devices

“…2(b) and its opto- electrical properties are described in our previous research. 13) Since the opto-electrical behaviors of white PLED is different from the normal semiconductor diode, two semiconductor diode (D 1 and D 2 ) with series resistors (R S1 and R S2 ) were used in parallel connection to fit the measured data of white PLED, and its equivalent circuit for the simulation is given in the insert. The a-Si:H TFTs and OLED parameters used for this pixel electrode circuit simulation are given in Table I.…”

Eletroluminescencia e morfologia de blendas polimericas

“…São muitos os polímeros conjugados utilizados em dispositivos eletroluminescentes (Tabela 1): poli(fenileno-vinilenos) 47 ; polifluorenos e seus derivados 48 ; politiofenos e seus derivados 49 O perfil e a largura dos espectros de absorção e de emissão em polímeros conjugados dependem do comprimento crítico de conjugação de cadeia e da distribuição de comprimentos. Esta distribuição pode ser alargada em altas temperaturas que diminuem a planaridade do sistema conjugado.…”