Organic bulk heterojunction solar cells based on benzodithiophene and benzothiadiazole containing conjugated polymers

Organic photovoltaics (OPVs) or so-called organic solar cells particularly hold promise for manufacturing solar energy due to their advantages in low cost and production processes. In order to understand and improve the performance of OPVs, intense efforts have been dedicated around the world [1]. In particular, conjugated polymers are attractive for OPVs due to the π-conjugated systems in the polymer backbone which generates and transport the charge carriers [2]. Therefore, the design and synthesis of novel conjugated organic polymers play important role to obtain higher photovoltaic properties and improve the power conversion efficiencies (PCEs) of the OPVs. For this purpose, benzodithiophene and benzothiadiazole containing monomers were independently synthesized, then polymerized via Stille cross-coupling reaction to obtain P1 and P2 polymers. Oxidation and reduction behavior of the polymers were studied by cyclic voltammetry. Measurements indicated that the highest occupied molecular orbital (HOMO) levels were -5.25 eV for P1 and -5.38 eV for P2. The optical band gaps of P1 and P2 were calculated via UV-VIS-NIR spectroscopy as 1.54 eV and 1.64 eV, respectively. Bulk heterojunction solar cells were constructed with these polymers as the donor moieties together with PC71BM as the acceptor in the active layer. The current/voltage measurements showed that the highest PCEs of these photovoltaic devices were recorded as 2.52% for P1: PC71BM (1:4, w/w) in 2% DIO and 1.67% for P2: PC71BM (1:3, w/w) in 3% DIO solution

Synthesis of selenophene substituted benzodithiophene and fluorinated benzothiadiazole based conjugated polymers for organic solar cell applications

© 2021A series of alternating conjugated copolymers which contain selenophene modified benzodithiophene and fluorine bearing benzothiadiazole have been synthesized via Stille polycondensation reaction to investigate the effect of the number of fluorine atoms substituted to the benzothiadiazole. Three different polymers, PBDTSe-BT, PBDTSe-FBT and PBDTSe-FFBT, were reported and their electrochemical, spectroelectrochemical, and photovoltaic behaviors were examined. Density functional theory calculations were performed on model tetramer structures to shed light on how substituting the fluorine atom to the acceptor building block affects the structural, electronic and optical properties of the polymers. The results of computational studies were compared with experimental studies. The structure adjustment accomplished by fluorine substitution on the benzothiadiazole moiety reveals an influence on the electronic structure of polymers with a more negative HOMO energy level. A high VOC for the resulting photovoltaic device was examined for PBDTSe-FFBT. Difluorinated polymer PBDTSe-FFBT:PC71BM organic solar cell exhibited the highest photovoltaic performance of 2.63% with JSC of 7.24 mA cm-2, VOC of 0.72 V and FF of 50.6%. PBDTSe-BT:PC71BM revealed the best PCE as 2.39%, and the device reached the highest efficiency up to 1.68% for PBDTSe-FBT:PC71BM

Pirol ve indol kondenze heterosiklik bileşiklerin altın katalizörlüğünde sentezi.

New methodologies were developed for the synthesis of pyrrolo- and indolo-oxazin1-one derivatives. In the first section of this thesis, various N-propargyl pyrrole and indole esters were efficiently converted into corresponding carboxylic acids which then underwent intramolecular cyclization reaction with AuCl3 to give 6-exo-dig cyclization products. In the second part of the study, 6-exo-dig pyrrolo- and indolo- oxazinone derivatives were treated with TFA in order to achieve double bond isomerization. Some of the 6-exo-dig cyclic double bonds underwent isomerization to 6-endo-cyclic compounds upon treatment with TFA. The experimental results were supported by DFT calculations. Moreover, the cyclization reaction of 1-prop-2-ynyl1H-pyrrole-2-carboxylic acid in the presence of alcohols catalyzed by Au(I) resulted in the formation of hemiacetals after cascade reactions.M.S. - Master of Scienc

Organik Işik Yayan Diyot Uygulamalari İçin Konjüge Polimerlerin Sentezi

Bu çalışmada kimyasal yöntemle benzotriazol ve selenofen üniteleri içeren yeni polimerler Suziki kenetlenme yöntemi ile sentezlenecektir. Sentezlenecek polimerler, NMR, IR, GPC, TGA ve DSC yöntemleriyle karakterize edilecektir. Sentezlenen polimerlerin temizleme işlemleri gerçekleştirildikten sonra dönüşümlü voltametri tekniği kullanılarak redoks davranışları araştırılacak ve HOMO-LUMO enerji seviyeleri hesaplanacaktır. Spektroskopik teknikler kullanılarak yapısal analizlerine bakılacak, çözeltideki ve filmdeki kopolimerlerin ışığı soğurma ve floresan özellikleri incelenecektir. İnce film morfolojileri AFM ve TEM kullanılarak analiz edilecektir. Termal ve çözelti tavlama yöntemlerinin morfolojiye etkisine bakılacaktır ve son olarak kalınlığın ve morfolojinin optimizasyonu yapıldıktan sonra OLED yapımı gerçekleştirilecektir. ITO ve PEDOT: PSS kaplı substratlar inert(azot dolu) bir atmosfere sahip (O2 < 0.1 ppm H2O < 0.1 ppm) eldivenli kabin sistemi içerisinde polimerlerin kaplanması ve metal kontakların eklenmesi gerçekleştirilerek gerekli hesaplanmalar yapılacaktır. Bunun yanında, polimerler silisyum yüzeyler üzerine kaplanarak elipsometri tekniği kullanılarak optimum kalınlıkları belirlenecektir