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Rajalingam Agneeswari,공민성,이지훈,Vellaiappillai Tamilavan,이원기,박성흠,진영읍 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.7
Electron donor and electron acceptor materials for solution-processable polymer solar cells (PSCs) should ideally exhibit a narrow band gap (Eg) and high solubility for improved performance. Herein, we synthesized two new near-infrared-absorbing alternating polymers, namely P(BTz-FQ) and P(BTz-DTFQ), via Stille polymerization of 4-butoxy-5-(4-butoxy-2-(trimethylstannyl)thiazol-5-yl)-2-(trimethylstannyl)thiazole and 5,8-dibromo-2,3-didodecyl-6,7-difluoroquinoxaline or 5,8-bis(5-bromothiophen-2-yl)-2,3-didodecyl-6,7-difluoroquinoxaline. The absorption spectra of P(BTz-FQ) and P(BTz-DTFQ) ranged from 300 to 900?nm with two distinct absorption maxima at 718 and 800?nm and 665 and 718?nm, respectively. Both polymers exhibited an identical Eg of 1.41?eV, which is the lowest value reported for quinoxaline-based polymers to date. Their highest occupied (?5.04 and ?5.09?eV) and lowest unoccupied (?3.63 and ?3.68?eV) molecular orbital levels were suitable for their use as electron donors along with the fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester, as the electron acceptor in PSCs. The maximum power conversion efficiencies obtained for the PSCs utilizing P(BTz-FQ) and P(BTz-DTFQ) were 0.51% and 0.71%, respectively. These findings demonstrate that thiazole and fluoroquinoxaline derivatives are promising materials for PSCs and other optoelectronic devices.
Rajalingam Agneeswari,노경환,VELLAIAPPILLAI TAMILAVAN,진영읍,박성흠,현명호 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.2
A pyrrole-based, imide-functionalized, electron-deficient monomer unit, 4,6-dibromo-2,5-dioctylpyrrolo[3,4-c]pyrrole-1,3(2H,5H )-dione (DPPD), was copolymerized with electron-rich 2,6-bis(trimethyltin)-4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene to afford the polymer P( BDT-DPPD ). The weight-averaged molecular weight (M w) of P( BDT-DPPD ) was 6.41 × 103 g/mol with a polydispersity index (PDI) of 1.32. P( BDT-DPPD ) displayed a broad absorption band from 300 to 600 nm with onset absorption at 596 nm in the film state. The calculated optical bandgap of P( BDT-DPPD ) was 2.08 eV, and the estimated highest occupied molecular orbital energy level of P( BDT-DPPD ) was −5.48 eV. The polymer solar cell (PSC) fabricated in the ITO/PEDOT:PSS/P( BDT-DPPD )/PC70BM (1:2 wt%)/Al configuration was found to give a maximum power conversion efficiency (PCE) of 1.46% with an open-circuit voltage (V oc) of 0.79 V, a current density (J sc) of 4.59 mA/cm2, and a fill factor (FF) of 40%.
Rajalingam Nagendran,Yoon Jae-Hyun,Yoon Bohyun,Hung Nguyen Bao,Kim Won-Il,Kim Hyunju,Park Byeong Yong,Kim Se-Ri 한국응용생명화학회 2021 Applied Biological Chemistry (Appl Biol Chem) Vol.64 No.2
This study was conducted to investigate the prevalence of coliforms and Escherichia coli across radish sprout production facilities in the Republic of Korea and to characterize isolated E. coli. A total of 324 samples were collected from three different radish sprout production units in spring and summer. Overall, the levels of coliforms were significantly higher (> 3.75 log CFU/g) in radish sprouts during summer season than in spring. E. coli was detected in the pre-harvest (50%) and post-harvest (39%) sprouts and water samples (33%) from farms B and C. Of the 48 E. coli isolates, five E. coli isolates were positive for the eaeA gene, indicative of EPEC O110, two isolates were eaeA-positive (EPEC ONT) and one isolate was ipaH-positive (ETEC O71). These three E. coli strains were identified as novel sequence types by the multilocus sequence-typing assay based on the combination of allelic profiles. In addition, the EPEC O110 isolates obtained from the stream water stored in container of farm C were toxic to Caenorhabditis elegans. It is necessary to implement safety measures during the production of radish sprouts to prevent E. coli outbreaks.
Rajalingam Agneeswari,김단비,Vellaiappillai Tamilavan,신찬기,박성흠,진영읍 한국고분자학회 2023 폴리머 Vol.47 No.1
A new alternating copolymer, poly(3,6-bis(thiophen-2-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-3,5-di(thiophen-2-yl)-1,2,4-oxadiazole (PDPP4TO), was prepared and their properties were compared with the reported polymer, poly(2,5-bis(2-hexyldecyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-3-hexyl-2-(5-(3-hexylthiophen-2-yl)thiophen-2-yl)thiophene (PDPP5T), with the aim understanding the effects of inserting oxadiazole units on diketopyrrolopyrrole (DPP)-based polymer backbone. Surprisingly, the properties of DPP-based polymers were found to drastically change after inserting oxadiazoles on their backbone. Noticeably, PDPP4TO exhibited higher bandgap (⁓0.3 eV), and consequently showed good complementary absorption with non-fullerene acceptors, and deeper highest occupied molecular orbital (HOMO, ⁓0.16 eV) compared to those of PDPP5T. However, the photovoltaic devices made using PDPP4TO offered a lower power conversion efficiency (PCE, ⁓0.94%) compared to that of PDPP5T (⁓4.6%). Whereas, the PDPP4TO-based photovoltaic devices provided a significantly higher open-circuit voltage (Voc) than that of the PDPP5T-based devices. These results indicate that the insertion of oxadiazoles on DPP-based polymer backbones results in an enormous difference in their properties.
Synthesis and Characterization of 1,2,4-Oxadiazole-Based Deep-Blue and Blue Color Emitting Polymers
Rajalingam Agneeswari,VELLAIAPPILLAI TAMILAVAN,현명호 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.2
Two donor-acceptor-donor monomers such as 3,5-bis(4-bromophenyl)-1,2,4-oxadiazole (BOB) and 3,5-bis(5- bromothiophen-2-yl)-1,2,4-oxadiazole (TOT) incorporating electron transporting and hole blocking 1,2,4- oxadiazloe moiety were copolymerized with light emitting fluorene derivative via Suzuki polycondensation to afford two new polymers, PFBOB and PFTOT, respectively. The optical studies for polymers PFBOB and PFTOT revealed that the band gaps are 3.10 eV and 2.72 eV, respectively, and polymer PFBOB exhibited a deep-blue emission while polymer PFTOT showed blue emission in chloroform and as thin film. The photoluminescence quantum efficiencies (Φf ) of polymers PFBOB and PFTOT in chloroform calculated against highly blue emitting 9,10-diphenylanthracene (DPA, Φf = 0.90) were 1.00 and 0.44, respectively.
Rajalingam Agneeswari,진영읍,Yoomi Ahn,Vellaiappillai Tamilavan,Danbi Kim,Insoo Shin,Hojun Yi,Chnan-gi Shin,Sung Heum Park 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.11
Herein, we demonstrate a facile technique for transforming a low-energy-convertingquinoxaline-based polymer into an efficient polymeric donor for non-fullereneacceptor-based organic solar cells (NFA-OSCs). Alternating copolymers, namelyP(BDTSi-DTfQ), incorporating electron-rich 4,8-bis(triisopropylsilylethynyl)-benzo[1,2-b:4,5-0]dithiophene (BDTSi) and electron-deficient 2,3-didodecyl-6-fluoro-5,8-di(thiophen-2-yl)quinoxaline (DTfQ) units were synthesized. The propertiesof P(BDTSi-DTfQ) were thoroughly studied and briefly compared tothose of the reported polymers, namely P(BDTSi-DTffQ), made up of BDTSi and2,3-didodecyl-6,7-difluoro-5,8-di(thiophen-2-yl)quinoxaline (DTffQ) units. PolymerP(BDTSi-DTfQ) exhibited a lower bandgap (Eg) and higher highest occupied andlowest unoccupied energy levels (HOMO and LUMO) than P(BDTSi-DTffQ). The estimatedEg and HOMO/LUMO for P(BDTSi-DTfQ) were 1.90 eV and 5.46 eV/3.56 eV, respectively, and for P(BDTSi-DTffQ) the same were 1.94 eV and5.58 eV/3.64 eV, respectively. Interestingly, the NFA-OSCs made from P(BDTSi-DTfQ) as the donor and NFA, namely ITIC, as the acceptor, gave a power conversionefficiency (PCE) of 3.68%, which is much higher than the PCE obtained(⁓0.75%) for the OSCs prepared by using the P(BDTSi-DTffQ):ITIC blend. Noticeably,the energy levels of P(BDTSi-DTfQ) were found to be favorable for efficient chargeseparation when it was blended with ITIC. This blend not only allowed a bettercharge separation at the donor/acceptor interfaces but also significantly loweredbimolecular recombination. The overall effect was to provide a higher PCE. However,P(BDTSi-DTffQ) showed mismatched energy levels with ITIC resulting in ahigher bimolecular recombination and lower PCE.