2,1,3-benzotiadiazol ̇içeren polimerlerin tasarımı,sentezi ve karakterizasyonu: köprüleme ünitelerinin optoelektronik özellikleri ve opv cihaz yapısına etkisi

Recently, conjugated polymers have obtained increasing popularity in a wide range of application areas such as electrochromic (EC) devices, biosensors, organic solar cells (OPVs) and organic light-emitting diodes (OLEDs). This popularity results from ease of processability, a good charge transporting capability, and broad optical absorption ability of the conjugated polymers. 2,1,3 benzothiadiazole has been commonly used in D-A type conjugated polymers since it is one of the strongest acceptor groups resulting in low band gap polymers. Fluorination of polymer backbone has appeared to be a promising approach for the development of semiconducting polymers for photovoltaic devices. Altering frontier molecular orbitals via fluorination could lead to better device performance. Alkoxy substitution is also performed to provide better solubility and high molecular weight for polymers. Besides, fluorene is used as a donor due to its high electron density and larger absorption wavelength. Lately, bridging groups are introduced into the polymer backbone to obtain higher intermolecular charge transport, higher absorption in the spectrum, and lower band gap. In this thesis, 2,1,3-benzothiadiazole coupled with bridging groups: furan, thiophene, 3-hexylthiophene, selenophene, and thienothiophene via Stille reaction. These groups are used to investigate the changes in electronic, optic, intermolecular charge transport, and photovoltaic properties of the polymers. GPC analyses are done to determine molecular weights of polymers. Redox behaviors of the polymers are studied using cyclic voltammetry. After optimizing thickness and morphologies of polymer: PCBM, device construction, and current-voltage property measurements are conducted in a nitrogen-filled glovebox system. The analysis of the photovoltaic devices (ITO/PEDOT:PSS/Polymer:PC70BM/Metal) is performed by means of the energy conversion efficiency measured under standard AM 1.5G illumination.