Organic semiconductors are of increasing interest as new materials for electronic devices, owing to their easy processing on flexible substrates and potential for low-cost fabrication. Organic light-emitting diodes (OLEDs), OLED display, photodiodes and field-effect transistors (FETs) are the electronic applications under the most intense study. This article is concerned with the recent advances of organic devices made of organic materials, as electrically and optically active components, in devices ranging from simple single-component OLEDs, through double- and multi-layer OLEDs to organic displays and OFET's.
Keywords: Organic light-emitting diodes, Organic FET, OLED display
[...] The application of printing technology as a fabrication tool indicates the potential of these novel materials for future electronic and opto-electronic applications This paper reviews the recent advances of organic devices made of organic materials, as electrically and optically active components, in devices ranging from simple singlecomponent OLEDs, through double- and multi-layer OLEDs to organic displays and OFET's. It is hoped that this paper would serve as a good starting point for those who want to explore this area and would like to know the status of the technology, the issues, the challenges, and research opportunities. [...]
[...] Extremely rapid advances in OLED efficiencies have been made since the early 1990s, with peak efficiencies of 70 lm/W in the green for molecular PHOLEDs. In contrast, the highest polymer OLED (PLED) efficiencies are -20 lm/W. Note that the OLED efficiencies are measured for devices on flat glass substrates, where the total out coupling is only -20%. This is compared to ultrahigh brightness inorganic AlInGaP red LEDs used in, among other applications, traffic signals, where nearly all emitted light is projected into the viewing direction, leading to external efficiencies approximately equal to their internal efficiencies. [...]
[...] There is a potentially important cost advantage associated with the solution processing of organic TFTs, because it eliminates the need for expensive vacuum chambers and lengthy pump-down cycles .The electronic and optical properties of these "active" organic materials are now suitable for some low performance, low-cost electronic products that can address the needs for lightweight portable devices for the 21st century and should be dominant in OLEDs flat panel displays, and perhaps in solid state illuminations. There will be continued growth in the field of organic electronics, fuelled by the promise of the new products and applications that can be derived from electronically and optically active organic and hybrid materials. [...]
[...] R. Brown, R. N. Marks, K. Mackay, R. H.Friend, P. R. Burn, A.B. Holmes, Nature H. Koezuka, A. Tsumura and T. Ando, Synthetic Metals Hoth, C.N, Choulis S.A., Schilinsky P and Brabec C. J., Advanced Materials pp (2007). Choulis, S.A. et al, to be published, Nanoletters, (2008) J. Kalinowski, J Phys. D. Appl. Phys R J. M. Shaw, P. M. Seidler, IBMJ. Res. & Dev [...]
[...] In particular, active matrix liquid crystal displays (AMLCDs) have efficiencies of 2 lm/W, compared to -10 lm/W for molecular organic phosphorescence (or PHOLED) based displays. Note that emissive display pixels are only turned on when needed, whereas LCD backlights must be fully on during use. Given that only of the pixels need to be illuminated when displaying a "typical" image, this alone provides for a significant power saving over LCDs. Then, given the very high efficiencies of PHOLEDs, even a greater advantage in power saving is realized. [...]
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