Property modulation of benzodithiophene-based polymers via the incorporation of a covalently bonded novel 2,1,3-benzothiadiazole-1,2,4-oxadiazole derivative in their main chain for polymer solar cells

Agneeswari, Rajalingam,Tamilavan, Vellaiappillai,Song, Myungkwan,Hyun, Myung Ho The Royal Society of Chemistry 2014 Journal of Materials Chemistry C Vol.2 No.40

<P>Two new electron accepting monomers (BBOBandBOB) containing two serially connected different electron deficient units, such as 2,1,3-benzothiadiazole and 1,2,4-oxadiazole, were prepared and copolymerized with electron-rich benzodithiophene (BDT) derivative to afford polymersP(BDT-BBOB)andP(BDT-BOB), respectively. The optical band gaps ofP(BDT-BBOB)andP(BDT-BOB)are calculated to be 2.32 eV and 1.99 eV, respectively, and their highest occupied molecular energy levels are determined to be −5.31 eV and −5.27 eV, respectively. Each of the newly synthesized polymers,<I>i.e.</I>P(BDT-BBOB)andP(BDT-BOB), is used as an electron donor, along with PC61BM as an electron acceptor, in the preparation of polymer solar cells (PSCs). The PSCs made with the configuration of ITO/PEDOT:PSS/P(BDT-BBOB)orP(BDT-BOB):PC61BM (1 : 2 wt%)/LiF/Al gave a maximum power conversion efficiency (PCE) of 1.76% and 2.46%, respectively, and the device performance was further improved to 3.31% and 4.21%, respectively, by simply treating the photoactive layer of PSCs with isopropyl alcohol. Overall, the opto-electrical and photovoltaic properties of the two polymers are found to be quite dependent on the configuration of the covalently bonded 2,1,3-benzothiadiazole and 1,2,4-oxadiazole units incorporated in the polymer main chain.</P>

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.

Preparation of a New Polymer Containing Benzodithiophene and Imide-functionalized Pyrrolo[3,4-c]pyrrole-1,3-dione Units for Polymer Solar Cells

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%.

Effects on the Properties of Diketopyrrolopyrrole-based Polymer via Inserting Oxadiazoles on Their Main Chains

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.

Imide-linked alkyl chain influence on the properties of pyrrole-based imide-functionalized polymers containing pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione and benzodithiophene units for polymer solar cells

Agneeswari, Rajalingam,Lee, Jihoon,Park, Sung Min,Cho, Shinuk,Jin, Youngeup,Park, Sung Heum,Hyun, Myung Ho Elsevier 2016 Synthetic metals Vol.220 No.-

<P><B>Abstract</B></P> <P>A series of pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (DPPD)-based polymers incorporating different alkyl side chains on the imide nitrogen were prepared to investigate the imide-linked alkyl side chain effects on the properties of DPPD-based polymers. DPPD derivatives with heptyl, octyl, decyl and dodecyl substituents on the imide nitrogen were prepared and copolymerized with 2,6-bis(trimethyltin)-4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene (BDT) to offer polymers P(BDT-C<SUB>7</SUB>-DPPD), P(BDT-C<SUB>8</SUB>-DPPD), P(BDT-C<SUB>10</SUB>-DPPD), and P(BDT-C<SUB>12</SUB>-DPPD), respectively. All four polymers displayed identical optical band gaps (<I>E<SUB>g</SUB> </I> ∼2.11eV) and highest occupied/lowest unoccupied molecular orbital energy levels (HOMO/LUMO∼−5.39eV/–3.28eV). The conventional single layer polymer solar cell (PSC) fabricated with a device structure of ITO/PEDOT:PSS/polymer:PC<SUB>70</SUB>BM (1:1.5wt%)/Al offered a power conversion efficiency (<I>PCE</I>) of 1.65%, 1.49%, 1.24%, and 0.87%, respectively. The PSC device performance was improved to 5.67%, 5.29%, 4.06%, and 2.46%, respectively, with the use of processive additive such as 1,8-diiodoocate (DIO).</P> <P><B>Highlights</B></P> <P> <UL> <LI> DPPD-based polymers containing different alkyl chains on the backbone were prepared. </LI> <LI> All polymers showed an identical band gap of 2.11eV. </LI> <LI> All polymers showed an identical HOMO/LUMO level of −5.39eV/–3.28eV. </LI> <LI> Photovoltaic performance of the polymers was dependent on the alkyl chain length. </LI> <LI> The morphology of the active layer was dependent on the alkyl chain length. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced photovoltaic performance for quinoxaline‐based polymeric donor via backbone engineering for non‐fullerene organic solar cells

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.

Synthesis and Characterization of 1,2,4-Oxadiazole-Based Deep-Blue and Blue Color Emitting Polymers

Agneeswari, Rajalingam,Tamilavan, Vellaiappillai,Hyun, Myung Ho Korean Chemical Society 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 (${\Phi}_f$) of polymers PFBOB and PFTOT in chloroform calculated against highly blue emitting 9,10-diphenylanthracene (DPA, ${\Phi}_f=0.90$) were 1.00 and 0.44, respectively.

Visible to Near-Infrared-Absorbing Polymers Containing Bithiazole and 2,3-Didodecyl-6,7-Difluoroquinoxaline Derivatives for Polymer Solar Cells

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.

Enhanced Photovoltaic Performance by Incorporating Quinoxaline-Based Polymer Donors via Non-Fullerene Backbone Engineering in Organic Solar Cells

안유미,( Rajalingam Agneeswari ),( Vellaiappillai Tamilavan ),박성흠 한국공업화학회 2023 한국공업화학회 연구논문 초록집 Vol.2023 No.0

Thiophene and thieno[3,2-b]thiophene π-bridged pyrrolo[3,4-c]pyrrole-1,3-dione-based wide band-gap polymers for fullerene and non-fullerene organic solar cells

Tamilavan, Vellaiappillai,Lee, Jihoon,Agneeswari, Rajalingam,Jung, Yun Kyung,Jin, Youngeup,Jeong, Jung Hyun,Hyun, Myung Ho,Park, Sung Heum Elsevier 2018 Organic Electronics Vol.63 No.-

<P><B>Abstract</B></P> <P>The conventional polymerization of 2,5-bis(trimethylstannyl)thiophene (T) or 2,5-bis(trimethylstannyl)thieno[3,2-b]thiophene (Tt) with 4,6-bis(5-bromothiophen-2-yl)-5-octyl-2-(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (TPPDT) afforded new alternating polymers, namely <B>P(T-TPPDT)</B> or <B>P(Tt-TPPDT)</B>, respectively. Both <B>P(T-TPPDT)</B> and <B>P(Tt-TPPDT)</B> exhibited similar thermal stabilities (5% weight loss at around 420 °C) and absorption maxima (<I>λ</I> <SUB>max</SUB> ≈ 515 nm) as films. The absorption bands of <B>P(T-TPPDT)</B> and <B>P(Tt-TPPDT)</B> extend between 300 and 620 nm, with optical band gaps (<I>E</I> <SUB> <I>g</I> </SUB>s) of 2.02 eV and 2.00 eV, respectively. The highest-occupied/lowest-unoccupied molecular-orbital energies of <B>P(Tt-TPPDT)</B> (HOMO/LUMO: −5.35 eV/–3.33 eV) were found to be somewhat higher than those of <B>P(T-TPPDT)</B> (HOMO/LUMO: −5.31 eV/–3.31 eV). Organic solar cells (OSCs) prepared using 1:1.5 (w/w) <B>P(T-TPPDT)</B>:PC<SUB>70</SUB>BM or <B>P(Tt-TPPDT)</B>:PC<SUB>70</SUB>BM (PC<SUB>70</SUB>BM = [6,6]-phenyl C<SUB>70</SUB> butyric acid methyl ester) blends provided power-conversion efficiencies (<I>PCE</I>s) of 3.50% or 4.71%, respectively. On the other hand, OSCs prepared with 1:1 (w/w) <B>P(T-TPPDT)</B>:ITIC or <B>P(Tt-TPPDT)</B>:ITIC (ITIC = 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)indanone))-5,5,11,11-tetrakis(4-hexylphenyl)dithieno[2,3-d:2′,3′-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene) blends exhibited improved <I>PCE</I>s of 5.32% or 6.35%, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two new polymers, <B>P(T-TPPDT)</B> and <B>P(Tt-TPPDT)</B>, were prepared. </LI> <LI> The optical band gaps were 2.02 eV and 2.00 eV. </LI> <LI> The HOMO/LUMO levels were −5.35 eV/‒3.33 eV and −5.31 eV/‒3.31 eV. </LI> <LI> The polymer:PC<SUB>70</SUB>BM blends offered a <I>PCE</I> of 3.50% and 4.71%. </LI> <LI> The polymer:ITIC blends provided a <I>PCE</I> of 5.32% and 6.35%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>