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

Received: 7 December 2009 / Accepted: 13 July 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

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*Corresponding author; email: fahmi982@gmail.com