Investigation of the effect of heteroatom and integration of boron on benzodithiophene and pyrazine containing conjugated polymers for photovoltaic applications

2021-7
Abacıoğlu, Yeşim
In the context of this thesis, two different subjects were investigated for photovoltaic applications of conjugated polymers; the effect of heteroatom and integration of boron. The element boron has received considerable attention in the research of alternative energy sources due to its superior properties, and incorporation of boron in conjugated systems is considered as an important strategy to achieve efficient photovoltaics. In this sense, benzodithiophene and pyrazine containing conjugated polymer was synthesized, and boron was embedded into the conjugated system using the post-polymerization borylation method which has been recently reported in the literature. Two polymers, non-borylated (P1A) and borylated (P1B) polymers were compared in terms of their electronic and optical properties for photovoltaic applications. Another concept, namely the effect of heteroatom, was investigated by altering one heteroatom on benzazole acceptor of benzodithiophene and pyrazine containing conjugated random polymers. Here, three different random polymers, benzotriazole-bearing RP1, benzothiadiazole-bearing RP2, and benzoselenadiazole-bearing RP3, were synthesized. For all polymers, electrochemical studies were carried out by cyclic voltammetry to calculate the HOMO and LUMO levels of the polymers, and UV-Vis Spectrophotometry analyzes were performed for optical studies. As a result of these studies, electronic and optical properties of all polymers were investigated. In this work, photovoltaic application studies of the polymers were carried out by using Polymer:PC71BM blend as an active layer in the construction of the bulk heterojunction solar cells. Power conversion efficiencies and blend film morphologies were investigated. As a result, poor power conversion efficiency values of 0.30% and 0.06% were obtained for non-borylated and borylated polymers, respectively. Finally, for random polymers, the highest power conversion efficiencies were obtained as a result of several optimizations as follows: 1.68% for RP1, 1.15% for RP2 and 2.14% for RP3.
Citation Formats
Y. Abacıoğlu, “Investigation of the effect of heteroatom and integration of boron on benzodithiophene and pyrazine containing conjugated polymers for photovoltaic applications,” M.S. - Master of Science, Middle East Technical University, 2021.