Syntheses of functional materials for organic photovoltaic and electrochromic device applications

Varlıoğlu, Figen
Thienothiophene based moities are widely investigated for organic solar cell applications. In this study, after synthesizing 2-ethylhexyl 4,6-dibromothieno [3,4-b]thiophene-2-carboxylate successfully, copolymerization with commercially available donor 4-(2-ethylhexyl)-2,6-bis(trimethylstannyl)-4H-dithieno[3,2-b:2',3'-d]pyrrole, DTPy, was performed via Stille coupling. At each step, Nuclear Magnetic Resonance (NMR) Spectroscopy were performed for structural analysis. Cyclic voltammogram was used for investigation of electrochemical behaviors. Oxidation potentials of the polymer were monitored at 0.25 V/ 0.81 V for p-doping and 0.08 V/ 0.52 V for p-dedoping. Moreover, spectroelectrochemical analysis was done in order to obtain λmax value which was determined to be 728 nm. Optical band gap was calculated to be 1.2 eV. This clearly shows that a strong NIR absorbing polymer was successfully synthesized. Kinetic studies show optical contrast of PTTDTPy is 14 % at 1055 nm and 17% at 720 nm with 1.43 at 1055 nm and 0.9 at 720 nm switching times. The performance of the polymer in organic solar cells is currently being investigated. In the field of conjugated polymer systems, PEDOT has a special place. PEDOT and its derivatives are used in a variety of applications, spanning from electrochromic devices to bulk-heterojunction solar cells. Even though there is an immense interest surrounding this family of compounds the long pursued symmetric bifunctional derivative PDiEDOT (poly-dithieno[3,4-b:3',4'-e][1,4]dioxine and ProSOT (poly-3,4-dihydro-2H-thieno[3,4-b]oxathiephine) have not been realized. An eight step synthesis was envisioned in this study for realization of DiEDOT. Seven steps of this synthesis were successfully completed. Future studies will be concerned with finalization of the synthesis and investigation of electrochemical and electrochromic properties. The novel corresponding monomer of ProSOT was successfully synthesized for the first time in this study. However the monomer was not electrochemically active. Hence this monomer was brominated and moiety was coupled with stannylated 3,4-ethylenedioxythiophene EDOT to realize a novel electroactive monomer. For structural analysis NMR spectroscopy and HRMS were used. Electrochemical polymerization was performed with cyclic voltammogram with 0.1 DCM/ACN/NaClO4/LiClO4 systems. Oxidation potentials of the polymer was detected at 0.26 V for p-doping and 0.04 V for p-dedoping. Spectroelectrochemical results reveal that λmax values were 515 nm and 555 nm and optical band gap of the polymer was calculated as 1.60 eV. Moreover, kinetic studies were conducted. At 515 nm, optical contrast of corresponding polymer was founded as 49% fast switching time of 0.8 seconds. This optical contrast value is superior to the corresponding homopolymer of EDOT, PEDOT.


Synthesis of novel diketopyrrole and selenophene containing nir absorbing polymers and their application in bulk-heterojunction solar cells
Öklem, Gülce; Günbaş, Emrullah Görkem; Department of Polymer Science and Technology (2017)
DPP-based conjugated polymers are recently used in organic light emitting diodes, electrochromic devices, organic field effect transistor and organic solar cell applications. Their advantageous properties, such as broad optical absorption in Near Infra Red (NIR) region, high charge carrier mobility and good film forming ability make them an excellent choice for generation of highly efficient solar cells. In this thesis, using donor-acceptor approach (D-A) we aimed to synthesize novel polymers with furan bas...
Polymer light emitting diodes and organic solar cells towards ito free devices and high efficiency devices using electrochemically synthesized polymers /
Hızalan Özsoy, Gönül; Toppare, Levent Kamil; Department of Chemistry (2017)
In this study, polymer based solar cells and polymer based light emitting diodes were constructed. In the third and fourth chapters of this study, effect of terminal units and effect of molecular weight on electroluminescence and photovoltaic properties were investigated. Triphenyl end capped polymer P1 based PLED shows luminance value of 10411cd/m2 at 8.5V whereas benzene end capped polymer P2 based PLED has the peak luminance value of 14583cd/m2 at 8V. P2 based photovoltaic devices exhibited superior perf...
Syntheses of benzodithiophene and thienopyrroledione containing conjugated random polymers as components for organic solar cells
Azeri, Özge; Çırpan, Ali; Department of Chemistry (2017)
In recent years organic solar cells (OSC) have attracted considerable attention as promising candidates for renewable energy technology because of their low cost, light weight and flexibility. In this study, in order to improve the efficiency of a bulk heterojunction solar cell, two conjugated random polymers were designed. For this purpose, benzodithiophene and thienopyrroledione containing two random copolymers were synthesized. The effects of several acceptors such as benzotriazole and benzothiadiazole o...
Syntheses and investigation of optoelectronic properties of benzothiadiazole and benzotriazole containing conjugated polymers
Keleş, Duygu; Çırpan, Ali; Arslan Udum, Yasemin; Department of Polymer Science and Technology (2017)
Benzothiadiazole is one of the most widely used acceptor units in Donor–Acceptor copolymers for organic solar cells (OSCs) with its strong electron withdrawing ability. It is also known that fluorine atom substitution directly to the backbone of conjugated polymers can improve the important parameters such as power conversion efficiency (PCE), open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF) of OSCs. Besides benzothiadiazole, benzotriazole is another acceptor moiety whic...
Synthesis, electrochemical characterization and organic solar cell applications of selenophene containing conjugated polymers
Yaşa, Mustafa; Toppare, Levent Kamil; Department of Polymer Science and Technology (2017)
Donor-Acceptor (D-A) type conjugated polymers are very popular for potential applications such as organic light emitting diodes, solar cells, electrochromic devices and organic field effect transistors. In literature, cyclopentadithiophene and its derivatives are commonly used electron donor units for organic solar cells. The incorporation of selenium atom into polymer backbone results in low band gap polymers as compared to sulfur and oxygen counterparts. In this study, selenophene containing conjugated po...
Citation Formats
F. Varlıoğlu, “Syntheses of functional materials for organic photovoltaic and electrochromic device applications,” M.S. - Master of Science, Middle East Technical University, 2017.