Investigation of electron transport layer and fluoride for the properties of organic solar cells

• Main Authors: Tsung-Chang Wang, 王宗昶
• Other Authors: Chien-Jung Huang
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/fu8884

碩士 === 國立高雄大學 === 應用物理學系碩士班 === 97 === The organic solar cells (OSC) have several superior advantages to inorganic solar cells, including lower cost, larger fabrication area, lighter weight and flexible property. Unfortunately, the power conversion efficiency (PCE) of the OSC is quite poor at the present time. Thus, improvement of PCE is an important issue. And then there are improvement methods of OSC from introduction of device concept such as change in active material, light harvesting structure, annealing and the electron transport layer (ETL). In this study, the structure of small-molecule OSC with is ITO-coated glass substrate /Copper phthalocyanine (CuPc) / fullerene (C60)/electron transport layer (ETL)/Al. The active layer is composed of CuPc and C60. 2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1, 3, 4-oxadiazole (PBD), Aluminum tris(8-hydroxyquinoline) (Alq3) and bathocuproine (BCP) are used as an electron transport layer. The materials of LiF and KF are used as a modification layer. In this study, the thicknesses of each material have been optimized for a better PCE. Besides, the short current density (Jsc) of devices with BCP layer was greatly improved compared with that of other ETL materials. The superior properties of BCP, such as lower electron injection barrier, higher UV/vis absorption efficiency and lower surface roughness, have been demonstrated by the energy level diagram, UV/vis absorption spectra and atom force microscope (AFM) data. In order to further improve the PCE of devices, we add ultra-thin fluoride as a modification layer to the devices with BCP layer. The PCE of OSC is improved from 0.54 % to 0.64 %.