Sains Malaysiana 40(2)(2011): 173–176

Determination of HOMO and LUMO of [6,6]-Phenyl C61-butyric Acid3-ethylthiophene Ester and Poly (3-octyl-thiophene-2, 5-diyl) through Voltametry Characterization

(Penentuan HOMO dan LUMO Asid [6,6]-Fenil C61-butirik Ester 3-etiltiofena dan Poli (3-oktil-tiiofena-2, 5-diyl) menerusi Pencirian Voltametri)

Ashkan Shafiee, Muhamad Mat Salleh*

Institute of Microengineering and Nanoelectronics (IMEN)

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E., Malaysia

Muhammad Yahaya

School of Applied Physics, Faculty of Science and Technology

University Kebangsaan Malaysia, 43600 Bangi, Selangor D.E., Malaysia

Diserahkan: 29 Disember 2009 / Diterima: 9 Julai 2010

ABSTRACT

HOMO and LUMO of organic compounds are basic parameters for the design and fabrication of an organic solar cell. This paper presents a technique to obtain HOMO and LUMO of an n-type polymer of [6,6]-phenyl C61-butyric acid 3-ethylthiophene ester (PCBE) and a p-type polymer of poly (3-octyl-thiophene-2, 5-diyl) (P3OT). The energy of band gap for each material has been calculated using optical absorption spectrum. Cyclic Voltammetry was used to estimate the oxidation potential and energy band diagram consequently. The experiments were carried out in a three-electrode cell consisting of a platinum working electrode, a platinum counter electrode and a SCE reference electrode. P3OT showed energy band gap equal to 1.83 eV with HOMO and LUMO equal to 5.59 eV and 3.76 eV, respectively. PCBE showed energy band gap equal to 1.96 eV with HOMO and LUMO equal to 5.87 eV and 3.91 eV, respectively. Based on energy band diagram that was constructed from this experimental result, the couple materials may be successfully used to fabricate the feasible organic solar cells.

Keywords: Cyclic voltametry; donor-acceptor materials; organic solar cells

ABSTRAK

HOMO dan LUMO adalah parameter asas dalam merekabentuk dan fabrikasi suatu sel suria organik. Kertas ini mengemukakan suatu teknik untuk mendapat HOMO dan LUMO suatu polimer jenis-n, asid [6,6]-fenil C61-butirik sster 3-etiltiofena (PCBE), dan suatu polimer jenis-p, poli (3-oktil-tiiofena-2, 5-diyl) (P3OT). Jurang jalur tenaga tiap-tiap bahan dikira daripada spektrum serapan optik. Voltametri berkitar diguna untuk menganggarkan keupayaan pengoksidaan dan seterusnya gambar rajah jalur tenaga. Uji kaji dijalankan menggunakan sel tiga-elektrod yang terdiri daripada suatu elektrod kerja platinum, satu elektrod lawan platinum dan elektrod rujukan SCE. Bagi P3OT jurang jalur tenaga adalah 1.83 eV dengan HOMO dan LUMO masing-masing berpadanan 5.59 eV dan 3.76 eV. Sementara itu PCBE telah menunjukkan jurang tenaga bersamaan 1.96 eV dengan HOMO dan LUMO masing-masing berpadanan 5.87 eV dan 3.91 eV. Berasaskan kepada gambar rajah yang dibina hasil eksperimen ini, dijangkakan gandingan dua bahan berkenaan dapat difabrikasi untuk menghasilkan sel suria organik yang baik.

Kata kunci: Bahan penderma-penerima; sel suria organik; voltometri berkitar

RUJUKAN

Al-Ibrahim, M., Roth, H.K., Schroedner, M., Konkin, A., Zhokhavets, U., Gobsch, G., Scharff, P. & Sensfuss, S. 2005. The influence of the optoelectronic properties of poly(3-alkylthiophenes) on the device parameters in flexible polymer solar cells. Organic Electronics 6: 65-77.

Al-Ibrahim, Konkin, A., Roth, H.K., Egbe, D.A.M., Klemm, E., Zhokhavets, U., Gobsch, G. & Sensfuss, S. 2005. Phenylene-ethynylene/phenylene-vinylene hybrid polymers: optical and electrochemical characterization, comparison with poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] and application in flexible polymer solar cells. Thin Solid Film 474: 201-210.

Hagfeldt, A. & Gratzel, M. 2000. Molecular photovoltaics. Accounts of Chemical Research 33(5): 269-277.

Hoppe, H. & Sariciftci, N.S. 2004. Organic solar cells: An overview. Journal of Material Research Society 19(7): 1924-1945.

Hwang, S.W. & Chen, Y. 2002. Photoluminescent and Electrochemical Properties of Novel Poly(aryl ether)s with Isolated Hole-Transporting Carbazole and Electron-Transporting 1,3,4-Oxadiazole Fluorophores. Macromolecules 35(14): 5438-5443.

Kietzke, T. 2007 Recent Advances in Organic Solar Cells. Advances in OptoElectronics. Article ID 40285.

Pommerehene, J., Vestweber, H., Guss, W., Mahrt, R.F., Bassler, H., Prorsch, M. & Daub, J. 1995. Efficient two layer LEDs on a polymer blend basis. Advanced Materials 7(6): 551-554.

Reyes-Reyes, M., Kim, K. & Carroll, D.L. 2005. High-efficiency photovoltaic devices based on annealed poly(3- hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1- phenyl-( 6,6)C61 blends. Applied Physics Letters 87(8): art. no. 083506 p. 1-3.

Schlaf, R., Schroeder, P.G., Nelson, M.W., Parkinson, B.A., Merritt, C.D., Crisafulli, L.A., Murata, H. & Kafafi, Z.H. 2000. Determination of interface dipole and band bending at the Ag/tris (8 hydroxyquinolinato) gallium organic Schottky contact by ultraviolet photoemission spectroscopy. Surface Science 450(1-2): 142-152.

Shafiee, A., Salleh, M.M. & Yahaya, M. 2008. Fabrication of organic solar cells based on a blend of donor-acceptor molecules by inkjet printing technique. IEEE International Conference on Semiconductor Electrionics, ICSE 2008: 319-322.

Shafiee, A., Salleh, M.M. & Yahaya, M. 2009. Fabrication of organic solar cells based on a blend of poly (3-octylthiophene-2, 5-diyl) and fullerene derivative using inkjet printing technique. Proc. SPIE, Vol. 7493, 74932D; doi:10.1117/12.843467

Shaheen, S.E., Brabec, C.J., Sariciftci, N.S., Padinger, F. & Fromherz, T. 2001. 2.5 % Efficient Organic Plastic Solar Cells. Applied Physics Letters 78(6): 841-843.

Xue, J., Rand, B.P., Uchida, S. & Forrest, S.R. 2005. Mixed donor acceptor molecular heterojunctions for photovoltaic applications. II. Device performance. Journal of Applied Physics 98(12): art no, 124903, pp. 1-9.

*Pengarang untuk surat-menyurat; email: mms@ukm.my