Opto-electronic properties of ITO/CuPc/NiPc/Al and ITO/NiPc/CuPc/Al double junction cells | ||||
| The International Conference on Electrical Engineering | ||||
| Article 76, Volume 6, 6th International Conference on Electrical Engineering ICEENG 2008, May 2008, Page 1-14 PDF (221.24 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/iceeng.2008.34317 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
| Kh. S. Karimov1; I. Qazi2; M. Mahroof-Tahir1; I. Murtaza2; T. Amin2; S. Z. Abbas2 | ||||
| 1St.Cloud State University, 720 Fourth Avenue South St.Cloud, MN 56301-4498, USA. | ||||
| 2GIK Institute of Engineering Science and Technology, Topi 23640, Swabi, N.W.F.P, Pakistan. | ||||
| Abstract | ||||
| Abstract: Thin organic semiconductor films of copper phthalocynanine (CuPc), Nickel Phthalocyanine (NiPc) and a metal (Al) were deposited on a conductive glass (ITO) substrate using vacuum evaporation technique to fabricate ITO/CuPc/NiPc/Al and a ITO/NiPc/CuPc/Al cells. These structures have double junction: heterojunctions (CuPc- NiPc, and NiPc-CuPc) and Schottky barrier (CuPc-Al, and NiPc-Al) junctions. This study investigates the effect of the thickness on the properties of the cells (The thicknesses of each organic semiconductor films in the three cells were equal to 25 nm, 50 nm and 75 nm.). The effective surface area of the samples was equal to 80 mm2 (8x10 mm2). The cells were carried through an annealing process at 150oC for 2 hrs and its effect on the properties of the cells was studied. The voltage-current characteristics under dark conditions as well as under filament lamp illumination were investigated. The open-circuit voltage (Voc) and short circuit current (Isc) illumination relationships, the dependences of photo-capacitance (Cph) on illumination and under modulated Red LED light frequency were studied. The absorbance of double CuPc/NiPc layer in the visible-IR spectrum was also examined. It was observed that the I-V characteristics rectification ratios was upto 13; the ratio of the photo- to dark-currents were in the range of 3-6; Voc and Isc reached 400 mV and 0.2 A respectively and the relative value of Cph increased by 50 % under illumination of 2000 lx. The frequency response of the Voc, Isc and Cph was investigated in the range 0-100 kHz. The Voc (DC) and Cph showed a frequency response up to 100 kHz, whereas Voc(AC)’s response was up to 100 Hz respectively. It was found that the overall performance of the ITO/NiPc/CuPc/Al cells is better than the ITO/CuPc/NiPc/Al cells. Using the experimental data, the charge transport mechanism in the double junction structures are discussed and the energy-banddiagram and an equivalent circuit were developed. | ||||
| Keywords | ||||
| Organic heterojunction cell; Schottky barrier; double junctions; opto-electronic properties; I-V characteristics; photo-electric cell; photocapacitance; open-circuit voltage; short-circuit current | ||||
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