%0 Journal Article
%T Investigation of Annealing and Blend Concentration Effects of Organic Solar Cells Composed of Small Organic Dye and Fullerene Derivative
%A Yasser A. M. Ismail
%A Tetsuo Soga
%A Takashi Jimbo
%J Advances in OptoElectronics
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/106276
%X We have fabricated bulk heterojunction organic solar cells using coumarin 6 (C6) as a small organic dye, for light harvesting and electron donation, with fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM), acting as an electron acceptor, by spin-coating technique. We have investigated thermal annealing and blend concentration effects on light harvesting, photocurrent, and performance parameters of the solar cells. In this work, we introduced an experimental method by which someone can easily detect the variation in the contact between active layer and cathode due to thermal annealing after cathode deposition. We have showed, in this work, unusual behavior of solar cell composed of small organic molecules under the influence of thermal annealing at different conditions. This behavior seemed uncommon for polymer solar cells. We try from this work to understand device physics and to locate a relationship between production parameters and performance parameters of the solar cell based on small organic molecules. 1. Introduction Organic solar cells have attracted much attention due to their potential in low-cost solar energy harvesting, as well as applications in flexible, light-weight, colorful, and large-area devices [1]. With the discovery of efficient photo-induced electron transfer from a conjugated polymer to fullerene [2], the bulk heterojunction (BHJ) organic solar cell has become one of the most successful device structures developed in the field to date. By simply blending electron donor with electron acceptor (fullerene) in organic solvents, a self-assembling interpenetrating network can be obtained using various coating technologies ranging from laboratory-scale spin-coating or spray-coating to large-scale fabrication technologies such as inkjet printing, doctor blading, gravure, slot-die coating, and flexographic printing. The BHJ solar cells performed with power conversion efficiency from solar light into electrical energy of up to about 6.1% [3], and with further progress, the efficiency reached about 6.8% [1]. To increase knowledge of material characteristics and behavior for photovoltaic applications, new BHJ systems should be studied. For significant improvements in organic solar cell efficiencies, new donor/acceptor combinations may be required to recognize and identify the photovoltaic properties of materials used in solar cells. To construct a new BHJ solar cell using low-molecular-weight compounds such as coumarin dyes, it is better first to illustrate the advantages of this kind of organic dyes. The coumarin dyes
%U http://www.hindawi.com/journals/aoe/2011/106276/