**Acknowledgement**

This work has been supported by the European Social Fund within the project «Support for the implementation of doctoral studies at Riga Technical University» and «Support for Doctoral Studies at University of Latvia» and by Latvian State Research Programm No.2 in Materials Sciences and Information Technologies. Authors are grateful to Janis Jubles for assistance on reactant synthesis, Kristine Lazdovica for absorption and emission measurements in solutions and conducting thermogravimetric analysis, Dr. chem. Baiba Turofska for electrochemical measurements, Kaspars Pudzs for activation energy measurements, Raitis Grzibovskis for photoelectrical measurements, Dr. phys. Saulius Jursenas for photoluminescence quantum yield measurements, Dr. phys. Vidmantas Gulbinas for useful discussion and Dr. phys. Mikelis Svilans for providing language help.

#### **5. References**

228 Organic Light Emitting Devices

red-emitters.

until now.

efficiency light emitting diodes.

Elmars Zarins and Valdis Kokars

Aivars Vembris and Inta Muzikante

**Author details** 

**Acknowledgement** 

Emission from the **IWK** film is too weak to detect, which may be attributed to the higher photoluminescence quenching in **IWK** than in glassy pyranylidene films. However, using the doping approach, the compounds we have introduced enable up to 3 times higher doping concentration without losing optical properties compared to other already known

Four investigated compounds - **ZWK-1**, **JWK-2**, **DWK-1** and **DWK-2** show amplified spontaneous emission from pure solid films. Obtained threshold values are larger than those previously reported, but it should be mentioned that for pyranylidene type compounds, amplified spontaneous emission has been observed only in the doped systems

Electrical properties are found to be better in compounds with one electron donor group due to absence of local trap states in their thin films. In the case of molecules with two electron donor groups shallow hole trap states have been observed, which may decrease efficiency of electroluminescence and should therefore be avoided in fabricating high

Even though we are able to prevent pyranylidene and isophorene type red-emitters from self crystallization in the solid state, their concentration in the emission layer would still be limited due to photoluminescence quenching caused by the short distance between molecules. Nevertheless, the glass materials can still be used not only as dopants for OLED applications, but also for lasing applications. Good thermal properties present a possibility

This work has been supported by the European Social Fund within the project «Support for the implementation of doctoral studies at Riga Technical University» and «Support for Doctoral Studies at University of Latvia» and by Latvian State Research Programm No.2 in Materials Sciences and Information Technologies. Authors are grateful to Janis Jubles for assistance on reactant synthesis, Kristine Lazdovica for absorption and emission measurements in solutions and conducting thermogravimetric analysis, Dr. chem. Baiba Turofska for electrochemical measurements, Kaspars Pudzs for activation energy measurements, Raitis Grzibovskis for photoelectrical measurements, Dr. phys. Saulius Jursenas for photoluminescence quantum yield measurements, Dr. phys. Vidmantas Gulbinas for useful discussion and Dr. phys. Mikelis Svilans for providing language help.

of using them also for nonlinear optical (NLO) property studies.

*Institute of Applied Chemistry, Riga Technical University, Riga, Latvia* 

*Institute of Solid State Physics, University of Latvia, Riga, Latvia* 


[17] R. Andreu, L. Carrasquer, J. Garin, M.J. Modrego, J. Orduna, R. Alicante, B. Vilcampa, M. Allian, New one- and two-dimensional 4*H*-pyranylidene NLO-phores. Tetrahedron Lett., 50, 2920-2924, (2009).

Synthesis and Physical Properties of Red Luminescent

Glass Forming Pyranylidene and Isophorene Fragment Containing Derivatives 231

[31] E. Zarins, V. Kokars, M. Utinans, Synthesis and properties of red luminescent 2-(3-(4- (bis(2-(trityloxy)ethyl)amino)styryl)-5,5-dimethylcyclohex-2-enylidene) malononitrile for organic light-emitting diodes. IOP Conf. Ser.: Mater. Sci. Eng. 2, 012-019, (2011). [32] A. Vembris, E. Zarins, J. Jubels, V. Kokars, I. Muzikante, A. Miasjedovas, J. Saulius, Thermal and optical properties of red luminescent glass forming symmetric and non symmetric styryl-4H-pyran-4- ylidene fragment containing derivatives. Opt. Mater.,

[33] R.H. Wiley, C.H. Jarboe, H.G. Ellert, Substituted 3-cinnamoyl-4-hydroxy-6-methyl-2-

[34] I.P. Lokot, F.S. Pashkovsky, F.A. Lakhvich, A New Approach to the Synthesis of 3.6 and 5,6-DIalyl Derivatives of 4-Hydroxy-2-pyrone. Synthesis or *rac*-Germicidin.

[35] M.L. Miles, C.R. Hauser, 2-(p-METOXYPHENYL)-6-PHENYL-4-PYRONE. Org. Synth.

[36] N.S. Vulfson, E.V. Sevenkova, L.B. Senyavina, Condensation of dehydroacetic acid with

[37] E. Zarins, V. Kokars, A. Ozols, P. Augustovs, Synthesis and properties of 1,3-dioxo-1*H*inden-2(3*H*)- ylidene fragment and (3-(dicyanomethylene)-5,5 dimethylcyclohex-1 enyl)vinyl fragment containing derivatives of azobenzene for holographic recording

[38] C. Jianzhong, H.J. Suh, S.H. Kim, Synthesis and properties of conjugated copolymers

[39] Z.R. Grabowski, K. Rotkiewicz, W. Rettig, Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer

[40] V.A. Pomogaev, V.A. Svetlichnyi, A.V. Pomogaev, N.N. Svetlichnaya, T.N. Kopylova, Theoretic and Experimental Study of Photoprocesses in Substituted 4-

[41] J.C. Mello, H.F. Wittmann, R.H. Friend, An improved experimental determination of external photolumiescence quantum efficiency. Adv. Mater. 9, 230-232, (1997). [42] P.R. Hammond, Laser dye DCM, its spectral properties, synthesis and comparsion with

[43] S.I. Bondarev, V.N. Knyukshto, V.I. Stepuro, A.P. Stupak, A.A. Turbanov, Fluorescence and Electronic Structure of the Laser Dye DCM in Solutions and in

[44] R. Kapricz, V. Getautis, K. Kazlauskas, S. Juršenas, V. Gulbinas, Multicoordinational excited state twisting of indan-1,3-dione derivatives. Chem. Phys., 351, 147-153, (2008). [45] V.G. Kozlov, S.R. Forrest, Lasing action in organic semiconductor thin films. Current

[46] A. Vembris, I. Muzikante, R. Karpicz, G. Sliauzys, A. Misajedovas, S. Jursenas, V. Gulbinas, Fluorescence and amplified spontaneous emission of glass forming

with 2- pyran-4-ylidene malononitrile. Dyes and Pigments, 68, 75-77, (2006).

Dicyanomethylene-4H-pyrans. High Energy Chemistry, 39, 403-407, (2005).

pyrones from dehydroacetic acid. J. Am. Chem. Soc., 77, 5102-5105, (1955).

34, 1501-1506, (2012).

Tetrahedron, 55, 4783-4792, (1999).

Coll., 5, 721 and 46, 60. (1973 and 1966).

http://www.orgsyn.org/orgsyn/pdfs/CV5P0721.pdf.

aromatic aldehydes. Rus. Chem. Bull., 15(9), 1541-1546, (1964).

materials. Proc. of SPIE, 8074, 80740E-1-80740E- 6, (2011).

States and Structures. Chem. Rev., 103, 3899-4031, (2003).

other dyes in the red. Opt. Commun., 29, 331-33, (1979).

Polymethylmetacrylate. J. Appl. Spectrosc., 71, 194-201, (2004).

opinion in Solid State and Materials Science 4(2), 203-208, (1999).


[31] E. Zarins, V. Kokars, M. Utinans, Synthesis and properties of red luminescent 2-(3-(4- (bis(2-(trityloxy)ethyl)amino)styryl)-5,5-dimethylcyclohex-2-enylidene) malononitrile for organic light-emitting diodes. IOP Conf. Ser.: Mater. Sci. Eng. 2, 012-019, (2011).

230 Organic Light Emitting Devices

787, (2009).

26, 223-229, (2004).

Pigments, 86, 149-154, (2010).

10.1039/c2cc31581e, (2012).

J. Lumin., 129, 1292–1297, (2009).

1, 011001-1-011001-8, (2011).

Mater. Res., 222, 271-274, (2011).

(2009).

DCJTB. Dyes and Pigments, 82, 316–321, (2009).

1,3-dione. Latvian J. Phys. Tech. Sci., 47(3), 23-30, (2010).

Lett., 50, 2920-2924, (2009).

[17] R. Andreu, L. Carrasquer, J. Garin, M.J. Modrego, J. Orduna, R. Alicante, B. Vilcampa, M. Allian, New one- and two-dimensional 4*H*-pyranylidene NLO-phores. Tetrahedron

[18] R. Andreu, S. Franco, E. Galįn, J. Garin, M.N. De Baroja, C. Momblona, J. Orduna, R. Alicante, B. Villacampa, Isophorone- and pyran-containing NLO-chromophores: a

[19] S. Wang, S.H. Kim, Photophysical and electrochemical properties of D-π-A type solvatofluorchromic isophorone dye for pH molecular switch. Curr. Appl. Phys., 9, 783-

[20] D.Y. Do, S.K. Park, J.J. Ju, S. Park, M.H. Lee, Nonlinear optical polyimides with various substituents on chromophores: synthesis and glass transition temperature. Opt. Mater.,

[21] P.J. Kim, O.P. Kwon, M. Jazbinsek, H. Yun, P. Gunter, The influence of pyrrole linked to the π-conjugated polyene on crystal characteristics and polymorphism. Dyes and

[22] P.Y. Chen, Y.U. Herng, M. Yokoyama, New double graded structure for enhanced performance in white organic light emitting diode. J. Lumin., 130, 1764–1767, (2010). [23] X.H. Zhang, B.J. Chen, X.Q. Lin, O.Y. Wong, C.S. Lee, H.L. Kwong, S.T. Lee, S.K. Wuu, A New Family of Red Dopants Based on Chromene-Containing Compounds for

[24] Z. Guo, W. Zhu, H. Tian, Dicyanomehtylene-4*H*-pyran chromphores for OLED emitters, logic gates and optical chemosensors. J. Mater. Chem., DOI:

[25] P. Zhao, H. Tang, Q. Zhang, Y. Pi, M. Xu, R. Sun, W. Zhu, The facile synthesis and high efficiency of the red electroluminescent dopant DCINB: A promising alternative to

[26] C.J. Huang, C.C. Kang, T.C. Lee, W.R. Chen, T.H. Meen, Improving the color purity and efficiency of blue organic light-emitting diodes (BOLED) by adding hole-blocking layer.

[27] H. Fukagawa, K. Watanabe, S. Tokito, Efficient white organic light emitting diodes with solution processed and vacuum deposited emitting layers. Org. Electron., 10, 798–802,

[28] A. Vembris, M. Porozovs, I. Muzikante, J. Latvels, A. Sarakovskis, V. Kokars, E. Zarins, Novel amourphous red electroluminescence material based on pyranylidene indene-

[29] A. Vembris, M. Porozovs, I. Muzikante, V. Kokars, E. Zarins, Pyranylidene indene-1,3 dione derivatives as an amorphous red electroluminescence material. J. Photon. Energy,

[30] E. Zarins, J. Jubels, V. Kokars, Synthesis of red luminescent non symmetric styryl-4Hpyran-4-ylidene fragment containing derivatives for organic light-emitting diodes*.* Adv.

Organic Electroluminescent Devices. Chem. Mater., 13, 1565-1569, (2001).

comparative study. Tetrahedron Lett., 51, 3662–3665, (2010).


compounds containing styryl-4H- pyran-4-ylidene fragment. J. Lumin., 132, 2421-2426, (2012).


(2012).

(1967).

compounds containing styryl-4H- pyran-4-ylidene fragment. J. Lumin., 132, 2421-2426,

[47] E.M. Calzado, J.M. Villalvilla, P.G. Boj, J.A. Quintana, R. Gomez, J.L. Segura M.A. Diaz Garcia, Amplified spontaneous emission in polymer films doped with a perylediimide

[48] J.Y. Li, F. Laquai, G. Wegner, Amplified spontaneous emission in optically pumped pure films of a polyfluorene derivative. Chem. Phys. Lett., 478, 37-41, (2009). [49] E.A. Silinsh, V.V. Capek, Organic Melecular Crystals. Interaction, localization and

[51] E.A. Silinsh, Organic Molecular Crystals Their Electronic States. Springer Series in

[52] A. Rose, Space-Charge-Limited Currents in Solids. Phys. Rev. 97, 1538-1655, (1955). [53] A. Rose, Concepts in Photoconductivity and Allied Problems. Interscience, New York,

[54] M.A. Lampert, P. Mark, Current Injectio in Solids. Academic Press, New York, (1970). [55] S. Nešpůrek, O. Zmeškal, J. Sworakowski, Space-charge-limited currents in organic

films: Some open problems. Thin Solid Films, 516, 8949, (2008).

derivative. Appl. Optic. 46, 3836-3842, (2007).

Solid-State Sciences 16, Berlin, (1980).

transport phenomena (AIP Press, New York), (1994). [50] E.A. Silinsh, M. Bouvet, J. Simon, Molecular Materials 51, (1995).
