Sains Malaysiana 40(1)(2011): 17–20

 

Tuning the Optical Band Gap of DH6T by Alq3 Dopant

(Penalaan Jurang Tenaga Optik DH6T dengan Menggunakan Bahan Pendop Alq3)

 

Fahmi Fariq Muhammad* & Khaulah Sulaiman

Department of Physics, Faculty of Science

University of Malaya, 50603 Kuala Lumpur, Malaysia

 

Diserahkan: 7 Disember 2009 / Diterima: 13 Julai 2010

 

ABSTRACT

 

Dihexyl-sexithiophene (DH6T) was doped with tris (8-hydroxyquinolinate) aluminum (Alq3) to prepare blends of DH6T/Alq3 by dissolving the mixture in the chloroform/hexane co-solvent. Solid films with different thickness deposited on quartz substrates were obtained from the blends via casting process. Optical absorption spectroscopy has been performed to measure the optical band gap of pure and doped DH6T as well as variations in the band gap with dopant concentration (weight %). This variation in optical band gap with dopant concentration was determined quantitatively with fitted and extrapolated techniques and observed qualitatively from the red shift appeared along the optical absorption spectra. The results showed that within a specific dopant content, the optical energy gap, Eg of DH6T decreases from 2.69 eV to 1.8 eV with increasing dopant concentration to 23.1%.

 

Keywords: Band gap tuning; dihexyl-sexithiophene; doping; optical properties

 

ABSTRAK

 

Diheksil-seksitiofena (DH6T) telah didopkan dengan tris (8-hidroksiquinolinat) aluminium (Alq3) bagi menyediakan adunan DH6T/Alq3 dengan melarutkan campuran-bahan dalam pelarut-bersama klorofom/heksana. Filem nipis yang berbeza ketebalan diperoleh melalui proses tuangan daripada campuran-bahan. Spektroskopi serapan optik dijalankan untuk mengukur jurang tenaga optik bagi DH6T yang tulen dan DH6T yang didopkan serta mengukur perubahan jurang tenaga dengan perubahan ketumpatan bahan pendop (% berat). Perubahan dalam jurang tenaga optik dengan ketumpatan pendop ini ditentukan secara kualitatif melalui teknik pemadanan dan ekstrapolasi serta pemerhatian secara kualitatif daripada anjakan merah bagi spetrum serapan optik. Keputusan menunjukkan bahawa jurang tenaga optik Eg DH6T pada kandungan bahan pendop tertentu telah berkurang daripada 2.69 eV kepada 1.8 eV bila ketumpatan meningkat kepada 23.1%.

 

Kata kunci: Diheksil-seksitiofena; penalaan jurang tenaga; pendopan, sifat optik

 

RUJUKAN

 

Bhat, S.V. & Deepak, F.L. 2005. Tuning the bandgap of ZnO by substitution with Mn2+, Co2+ and Ni2+. Solid State Communications 135: 345-347.

Chen, Z., Ikeda, S. & Saiki, K. 2006. Sexithiophene films on cleaved KBr(100) towards well-ordered semiconducting films. Materials Science and Engineering B 133: 195-199.

Dalasinski, P., Łukasiak, Z. Wojdyła, M. Rebarz, M. & Bała, W. 2006. Study of optical properties of TRIS (8-hydroxyquinoline) aluminum (III). Optical Materials 28: 98-101.

Horowitz, G., Romdhane, S., Bouchriha, H., Delannoy, P., Monge, J.L., Kouki, F. & Valat, P. 1997. Optoelectronic properties of sexithiophene single crystals. Synthetic Metals 90: 187-192.

Hwang, D.H. Chang, J.H. Shim, H.K. & Zyung, T. 2001. Band gap tuning of PPV derivatives by thiophenoxy precursor polymer. Synthetic Metals 119: 393-394.

Liu, X., Knupfer, M. & Huisman, B.H. 2005. Electronic properties of the interface between α, ω-dihexyl-quaterthiophene and gold. Surface Science 595: 165-171.

Lopez, M.B.O., Lerma, M.S. & Galvan, A.M. 2004. Optical band gap tuning and study of strain in CdS thin films. Vacuum 76: 181-184.

Marks, R.N., Muccini, M., Lunedi, E., Michel, R.H., Murgia, M., Zamboni, R., Taliani, C., Horowitz, G., Gamier, F., Hopmeier, M., Oestreich, M. & Mahrt, R.F. 1998. Disorder influenced optical properties of ot-sexithiophene single crystals and thin evaporated films. Chemical Physics 227: 49-56.

Michinobu, T., Okoshi, K. & Osako, H. 2008. Band-gap tuning of carbazole-containing donoreacceptor type conjugated polymers by acceptor moieties and π-spacer groups. Polymer 49: 192-199.

Muccini, M. 1998. Low energy electronic and optical properties of α-sexithiophene single crystals. Materials Science and Engineering C 5: 173-177.

Murphy, A.R., Frechet, J.M.J., Chang, P., Lee, J. & Subramanian, V. 2004. Organic Thin Film Transistors from a Soluble Oligothiophene Derivative Containing Thermally Removable Solubilizing Groups. Journal of American Chemistry Society. JACS Communications 10.1021/ja039529x CCC.

Sato, T., Fujitsuka, M., Shiro, M. & Tanaka, K. 1998. Photoluminescence quenching in oligothiophene single crystal. Synthetic Metals 95: 143-148.

Sotgiu, G., Zambianchi, M., Barbarella, G. & Botta, C. 2002. Synthesis and optical properties of soluble sexithiophenes with one central head-to-head junction. Tetrahedron 58: 2245-2251.

Tavazzi, S., Barbarella, G., Borghesi, A., Meinardi, F., Sassella, A. & Tubino, R. 2001. Absorption coefficient of sexithiophene thin films grown by organic molecular beam deposition. Synthetic Metals 121: 1419-1420.

Varghese, S. Iype, M. Mathew, E.J. & Menon, C.S. 2002. Determination of the energy band gap of thin films of cadmium sulphide, copper phthalocyanine and hybrid cadmium sulphide/copper phthalocyanine from its optical studies. Materials Letters 56: 1078-1083.

Wu, M.W. & Conwell, E.M. 1997. Transport in α-sexithiophene films. Chemical Physics Letters. 266: 363-367.

Yakuphanoglu, F. 2007. Electrical conductivity and electrical modulus properties of α, ω-dihexylsexithiophene organic semiconductor. Physica B 393: 139-142.

Yang, C. & Holdcroft, S. 1997. Thermochromism and Band-Gap Tuning of Acrylated Poly (3-alkylthiophenes). Synthetic Metals 84: 563-564.

 

*Pengarang untuk surat-menyurat; email: fahmi982@gmail.com

 

 

 

sebelumnya