Excimers and exciplexes in organic electroluminescence

• Autorzy: Kalinowski J.
• Języki publikacji: EN

Abstrakty

EN

In organic light emitting devices (LEDs) various types of emissive states are created: (i) molecular excited states (localized excitons), or bimolecular (B-M) species: excimers, electromers, exciplexes and electroplexes. The consequences of the formation of B-M excited species for optical and electrical characteristics of organic LEDs are discussed and illustrated by various examples. While molecular excitons can be viewed in some sense as correlated electron-hole (e-h) pairs with the inter-charge mean separation less than an intermolecular spacing, the size of B-M excited states amounts usually to one or two intermolecular spacings. The B-M species can be classified as electrically balanced states, formed under energy and charge exchange between neighbour molecules, and have either a singlet or a triplet character. The focus of the paper is on excimer and exciplex forming single phosphorescent dopant blends-based emitting layers but characteristic features of other B-M excited species (electromers and electroplexes) and their emissions are also mentioned. Of particular interest in modern optoelectronics are white and infrared organic LEDs. It is shown how excimer and exciplex emissions can be employed in manufacturing such devices. Examples include efficient white and near-infrared LEDs, based on single dopant emitters of an efficient N-C-N-coordinated platinum(II) complex phosphor, and their improved versions, obtained by modification of the emitter matrix materials and electron injecting electrodes.

Słowa kluczowe

EN

organic electroluminescence; organic LEDs; bimolecular excited states; near-infrared; white

• Wydawca: De Gruyter
• Czasopismo: Materials Science Poland
• Rocznik: 2009
• Tom: Vol. 27, No. 3
• Strony: 735--756
• Opis fizyczny: Bibliogr. 20 poz.

Twórcy

autor

Kalinowski J.

• Gdańsk University of Technology, 80-952 Gdańsk, Poland

Bibliografia

• [1] POPE M., SWENBERG C.E., Electronic Processes in Organic Crystals, Clarendon Press, Oxford, 1982.
• [2] KALINOWSKI J., Organic Light Emitting Diodes: Principles, Characteristics and Processes, Marcel Dekker, New York, 2005.
• [3] BIRKS J.B., Photophysics of Aromatic Molecules, Wiley, New York, 1970.
• [4] FÖRSTER T., Excimers and Exciplexes, [in:] The Exciplex, M. Gordon, W.R. Ware (Eds.), Academic Press, New York, 1975, p. 1.
• [5] KALINOWSKI J., COCCHI M., VIRGILI D., FATTORI V., WILLIAMS J.A.G., Chem. Phys. Lett., 447 (2007), 279.
• [6] KALINOWSKI J., GIRO G., COCCHI M., FATTORI V., DI MARCO P., Appl. Phys. Lett., 76 (2000), 2352.
• [7] KALINOWSKI J., GIRO G., COCCHI M., FATTORI V., ZAMBONI R., Chem. Phys., 277 (2002), 387.
• [8] HOFMANN J., SEEFELD K.P., HOFBERGER W., BAESSLER H., Mol. Phys., 37 (1979), 973.
• [9] FERGUSON A., MAU A.W.H., Mol. Phys., 27 (1974), 377.
• [10] FERGUSON A., MAU A.W.H., Mol. Phys., 28 (1974), 1467.
• [11] KALINOWSKI J., GODLEWSKI J., CHANCE R.R., J. Chem. Phys., 64 (1976), 2389.
• [12] KALINOWSKI J., Opt. Mater., 30 (2008), 792.
• [13] COCCHI M., KALINOWSKI J., VIRGILI D., WILLIAMS J.A.G., Appl. Phys. Lett., 92 (2008), 113302.
• [14] COCCHI M., VIRGILI D., FATTORI V., WILLIAMS J.A.G., KALINOWSKI J., Appl. Phys. Lett., 90 (2007), 023506.
• [15] COCCHI M., KALINOWSKI J., VIRGILI D., FATTORI V., DEVELAY S., WILLIAMS J.A.G., Appl. Phys.Lett., 90 (2007), 163508.
• [16] GIRO G., COCCHI M., KALINOWSKI J., DI MARCO P., FATTORI V., Chem. Phys. Lett., 318 (2002), 137.
• [17] KALINOWSKI J., COCCHI M., VIRGILI D., FATTORI V., WILLIAMS J.A.G., Chem. Phys. Lett., 432 (2006), 110.
• [18] VIRGILI D., COCCHI M., FATTORI V., SABATINI C., KALINOWSKI J., WILLIAMS J.A.G., Chem. Phys. Lett., 433 (2006), 145.
• [19] COCCHI M., VIRGILI D., SABATINI C., KALINOWSKI J., Chem. Phys. Lett., 421 (2006), 351.
• [20] KALINOWSKI J., COCCHI M., VIRGILI D., FATTORI V., WILLIAMS J.A.G., Adv. Mater., 19 (2007), 4000.