Abstract
The influence of polar dopant on the charge carrier transport in amorphous tris (8-hydroxyquinolinato) aluminum (Alq3) was studied by time-of-flight measurement. The 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) was doped into Alq3 with various concentration from 0.5 to 24 wt. %. The electron mobility was reduced by about one order by DCM doping in Alq3. The electric-field dependence electron mobility in Alq3:DCM films separated into two discrete regions of critical fields Ec 1/2. The value of Ec 1/2ranged from 360 to 405 (V/cm)1/2 depending on the DCM concentration in Alq3 films. The energetic disorder in Alq3:DCM films increased from 0.01 eV to 0.09 eV with DCM doping concentration. The positional disorder in Alq3:DCM films also increased from 0.3 to 6.5 with DCM doping concentration up to 24 wt. %. These results indicated the strong Coulombic and dipole–dipole interactions between DCM and Alq3 molecules. The interactions between randomly located DCM molecules, Alq3 dipoles and oriented dipoles are the major caused of positional disorder.
Similar content being viewed by others
References
Tang CW, VanSlykex SA, Chen CH (1989) J. Appl. Phys. 65:3610
Jung BJ, Yoon CB, Shim HK, Do LM, Zyung T (2001) Adv. Funct. Mater. 11:430
Bohler A, Urbach P, Schobel J, Dirr S, Johannes HH, Wiese S (1998) Physica E 2:562
Forrest SR (1997) Chem. Rev. 97:1793
Zhong GY, He J, Zhang ST, Xu Z, Xiong ZH, Shi HZ, Ding XM, Huang W, Hou XY (2002) Appl. Phys. Lett. 80:4846
Zhong GY, Xu Z, He J, Zhang ST, Zhan YQ, Wang XJ, Xiong ZH, Shi HZ, Ding XM, Huang W, Hou XY (2002) Appl. Phys. Lett. 81:1122
Littman J, Martic P (1992) J. Appl. Phys. 72:1957
Baldo MA, O’Brien DF, Thompson ME, Forrest SR (1999) Phys. Rev. B 60:14422
Berggren M, Dodabalapur A, Slusher RE (1997) Appl. Phys. Lett. 71:2230
Ermer S, Valley JF, Lytel R, Lipscomb GF, Van Eck TE, Girton DG (1992) Appl. Phys. Lett. 61:2272
Sworakowski J (1999) Brazil. J. Phys. 29:318
Arkhipov VI, Emelianova EV, Heremans P, Adriaenssens GJ (2002) J. Optoelecton. Adv. M. 4:425
Emelianova EV, Adriaenssens GJ (2004) J. Optoelecton. Adv. M. 6:1105
Borsenberger PM, Pautmeir LT, Bassler H (1993) Phys. Rev. B 48:3066
Lee CB, Uddin A, Hu X, Andersson TG (2004) Mat. Sci. Eng. B 112:14
Lee CB, Uddin A, Zhao XY, Phys. Rev. B (submitted)
Malliaras GG, Shen Y, Dunlap DH, Murata H, Kafafi ZH (2001) Appl. Phys. Lett. 79:2582
Scott JC, Pautmeier LT, Schein LB (1992) Phys. Rev. B 46:8603
Eisberg RM (1961) Fundamentals of Modern Physics. Wiley, New York
Kepler RG, Beeson PM, Jacobs SJ, Anderson RA, Sinclair MB, Valencia VS, Cahill PA (1996) Appl. Phys. 79:7991
Naka S, Okada H, Onnagawa H, Yamguchi Y, Tsutsui T (2000) Synth. Met. 111:331
Bassler H (1993) Phys. Stat. Solidi B 175:15
Author information
Authors and Affiliations
Corresponding author
Additional information
PACS
73.50.-h; 73.61.Ph; 71.20.Rv
Rights and permissions
About this article
Cite this article
Lee, C., Uddin, A. & Teo, C. Effect of polar dopant on energetic and positional disorders in tris(8-hydroxyquinolinato) aluminum (Alq3). Appl. Phys. A 83, 115–121 (2006). https://doi.org/10.1007/s00339-005-3467-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00339-005-3467-y