Nanomaterials and nanocomposites

Photoluminescence and electroluminescence from tailored Alq3:DCM nanolayers 
I. Karbovnyk1, B. Turko1, B. Sadovyi1, A.M. Kostruba2, H. Klym3, M. Rudko1, A.V. Kukhta4
1 Ivan Franko National University of Lviv, Dragomanova Str., 50, Lviv, 79005, Ukraine,
E-mail: ivan_karbovnyck@yahoo.com
2 Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies Lviv, 50, Pekarska Str., 79000, Lviv, Ukraine
3 Lviv National Polytechnic University, Lviv, Ukraine
4 Institute for Nuclear Problems, Belarusian State University, Minsk, Belarus

We discuss a successful attempt of creating complex nanostructures based on thin organic molecules layers and apparently suitable for OLED fabrication [1]. Organic films with the thickness less than 50 nm were thermally deposited under 10−4 Pa vacuum either onto substrates made of optical glass which is transparent for wavelengths above 300 nm or on transparent conductive indium-tin-oxide (ITO) glass. For the purpose of OLED functionality testing, electrical contacts at the top side of the designed structure (40 nm Alq3 layer) were formed by thermal evaporation of Al.  
The obtained structures were subjected to comprehensive optical investigations including ellipsometry, low temperature photoluminescence and room temperature electroluminescence measurements. The decay time curves for DCM-5 thin film photoluminescence bands were also recorded.
The electroluminescent emission of the ITO/Alq3:DCM-5 (10 wt. %)/Alq3/Al heterostructure was studied for different injected current levels ranging between 0.12 and 0.18 mA/cm2. It is shown, by using CIE (x, y) color coordinates representation, that the fabricated structure emits “warm” white light with an equivalent temperature of T = 3050 K.
Further experiments on the study of polarized emission from structures of this type are now underway. 

1.	Mori T., Obata K, Mizutani T.  Electroluminescence of organic light emitting diodes with alternately deposited dye-doped aluminium quinoline and diamine derivative // J. Phys. D: Appl. Phys. – 1999. –32. – P. 1198–1203.