Ladder-type heteroacene polymers bearing carbazole and thiophene ring units and their use in field-effect transistors and photovoltaic cells

Cheedarala, Ravi Kumar,Kim, Gi-Hwan,Cho, Shinuk,Lee, Junghoon,Kim, Jonggi,Song, Hyun-Kon,Kim, Jin Young,Yang, Changduk Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.3

<P>A family of ladder-type π-excessive conjugated monomer (dicyclopentathienocarbazole (DCPTCz)) integrating the structural components of carbazole and thiophene into a single molecular entity is synthesized and polymerized by oxidative coupling to yield poly(dicyclopentathienocarbazole) (PDCPTCz). Moreover, through the careful selection of 2,1,3-benzothiadiazole unit as a π-deficient building block, the dicyclopentathienocarbazole-based donor–acceptor copolymer (poly(dicyclopentathienocarbazole-<I>alt</I>-2,1,3-benzothiadiazole) (PDCPTCz-BT)) is prepared by Suzuki polycondensation. The optical, electrochemical, and field-effect charge transport properties of the resulting polymers (PDCPTCz and PDCPTCz-BT) are not only characterized in detail but also their bulk-heterojunction (BHJ) solar cell in combination with PC<SUB>71</SUB>BM are evaluated. The values of field-effect mobility (<I>µ</I>) for PDCPTCz and PDCPTCz-BT are 8.7 × 10<SUP>−6</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and 2.7 × 10<SUP>−4</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively. A power conversion efficiency (PCE) of 1.57% is achieved on the PDCPTCz-BT<B>/</B>PC<SUB>71</SUB>BM device, implying that the push–pull copolymers based on ladder-type dicyclopentathienocarbazole as an electron-donating moiety are promising for organic electronic devices.</P> <P>Graphic Abstract</P><P>A series of ladder-type heteroacene polymers based on dicyclopentathienocarbazole, <I>i.e.</I> poly(dicyclopentathienocarbazole) (PDCPTCz) and poly(dicyclopentathienocarbazole-alt-2,1,3-benzothiadiazole) (PDCPTCz-BT), is described for use in electronic applications. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm01897j'> </P>

Double characteristic BNO-SPI-TENGs for robust contact electrification by vertical contact separation mode through ion and electron charge transfer

Cheedarala, Ravi Kumar,Duy, Le Chau,Ahn, Kyoung Kwan unknown 2018 Nano energy Vol.44 No.-

<P><B>Abstract</B></P> <P>• Contact-electrification is a conventional triboelectrification technique for generating current through charge transfer when two different polarized materials are brought into contact. For the first time, in-built alternate hydrophilic and hydrophobic nano channels were developed where both ionic and electronic charge transfer mechanisms were realized through contact separation mode between BNO-SPI films and PTFE. In this paper, we examined the dynamic interaction between these materials and observed adequate output performance. The novel BNO-SPI-TENGs (i.e. SO3H.BNO-SPI-TENG, SO3Li.BNO-SPI-TENG, and SO3H.TEA.BNO-SPI-TENG) produced 75V and 1µA, 43V and 0.6µA, and 9V and 0.13µA of open-circuit voltages (Voc) and short-circuit currents (Jsc) at 6Hz, respectively. Particularly, the SO3H-BNO-SPI was dramatically boosted up the performance of TENG, up to 733% of Voc and 669% of Jsc, with respect to the SO3H.TEA-BNO-SPI because the mobility of H+ ions is very high on the device surface compared to the other two Li+ and TEA bulky ions. The developed dual characteristic BNO-SPI-TENGs are very good candidates for fulfilling the need for alternate contact separation mode TENGs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel double characteristic hydrophilic and hydrophobic nano channel oriented BNO-SPI films were proposed. </LI> <LI> Contact electrification process was took place on the BNO-SPI films that followed ion and electron transfer mechanisms. </LI> <LI> An electron-donor-acceptor complex mechanism was proposed for the electron transfer mechanism. </LI> <LI> High triboelectric (V<SUB>oc</SUB>) and (J<SUB>sc</SUB>) were observed from BNO-SPI-TENGs, in particular, 75V and 1µA for SO<SUB>3</SUB>H.BNO-SPI-TENG at 6Hz. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electric impulse spring-assisted contact separation mode triboelectric nanogenerator fabricated from polyaniline emeraldine salt and woven carbon fibers

Cheedarala, Ravi Kumar,Parvez, Abu Naushad,Ahn, Kyoung Kwan Elsevier 2018 Nano energy Vol.53 No.-

<P><B>Abstract</B></P> <P>In this article, we used modified woven carbon fiber mat (wCF-COOH), as one of the contact-electrification Triboelectric Nanogenerator (TENG) friction layer to generate high open circuit voltage (V<SUB> <I>oc</I> </SUB>) and short circuit current (I<SUB> <I>sc</I> </SUB>). We designed the contact-separation mode TENG which is functional using spring structure. The oxidation of wCF into wCF-COOH by Piranha solution followed by coupling of aniline through electrostatic interactions and in-situ oxidative polymerization to get woven carbon fiber-polyaniline emeraldine salt (wCF.PANI.ES) composite is a novel approach. The wCF-PANI.ES composite displays the surface resistivity of 0.324 Ω m and serves as a friction layer to generate charges by harvesting energy through vertical contact-separation mode TENG against PVDF membrane. The dynamic interactions of novel wCF-PANI.ES and PVDF membrane produced high V<SUB> <I>oc</I> </SUB> of 95 V, and I<SUB> <I>sc</I> </SUB> of 180 μA, respectively. In particular, wCF-PANI.ES-TENG has shown an enhancement of 498% of V<SUB> <I>oc</I> </SUB> with respect to wCF-COOH-TENG due to availability of PANI layer. In addition, it was observed that the proposed wCF-PANI.ES-TENG has shown the output power of 12.4 mW at 5 Hz, and the rectified current upto 180 μA. The novel wCF-PANI.ES is the potential candidate for fulfilling the need of optimized energy harvesting device as an alternate material option for contact-separation mode TENGs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> wCF-PANI.ES and PVDF based contact-separation mode spring assisted TENG was developed. </LI> <LI> wCF-COOH was generated from neat wCF cloth using Piranha solution followed by coupling of aniline by electrostatically and then in-situ oxidation polymerization produced the wCF-PANI.ES composite. </LI> <LI> High triboelectric (V<SUB> <I>oc</I> </SUB>) and (J<SUB> <I>sc</I> </SUB>) were attained from wCF-PANI.ES-TENG, in particular, 95 V and 180 µA at 5 Hz, respectively. </LI> <LI> The proposed wCF-PANI.ES-TENG has shown the output power of 12.4 mW at 5 Hz, and the rectified current upto 180 μA. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Donor spacer Acceptor Block Copolymer containing Both poly and perylene tetracarboxydimide

이정훈,Ravi Kumar Cheedarala,양창덕 한국고분자학회 2010 한국고분자학회 학술대회 연구논문 초록집 Vol.2010 No.4

Ladder-Type Heteroacene Polymers Bearing Carbazole and Thiophene Ring Units and Their Use in Field-Effect Transistors and Photovoltaic Cells

김경식,Ravi Kumar Cheedarala,김기환,이정훈,김종기,김진영,양창덕 한국고분자학회 2010 한국고분자학회 학술대회 연구논문 초록집 Vol.2010 No.10

A study of sustainable green current generated by the fluid-based triboelectric nanogenerator (FluTENG) with a comparison of contact and sliding mode

Nahian, Syed Abu,Cheedarala, Ravi Kumar,Ahn, Kyoung Kwan unknown 2017 Nano energy Vol.38 No.-

<P><B>Abstract</B></P> <P>Recently, the triboelectric nanogenerator (TENG) has become a well-known energy harvester for ambient-resource energy harvesting for which the contact electrification between two different materials is employed. Alternatively, research has been carried out on the fluid-based TENG (FluTENG) for the replacement of the conventional solid-based TENG due to the destruction of the active surface by a long mechanical rupture that reduces the triboelectrical effect. For the first time, a simple, eco-friendly, very economical, and novel DI (deionized)-water commercial-polytetrafluoroethylene (cPTFE)-based FluTENG with contact-separation (CS-FluTENG) and lateral-sliding (LS-FluTENG) modes has been developed for this paper. Here, we examined the dynamic interaction between water and solid contact for each mode. During the study of the surface morphologies for both the CS-FluTENG and the LS-FluTENG, an FE-SEM analysis showed expansions of the fibril lengths in the film network. Also, the mechanistic approach of water splitting and the way that a chemical reaction occurs with the cPTFE film during the contact electrification that have been proved by UV-spectroscopy, FT-IR, and XRD analyses were investigated in this manuscript. The contact-angle measurements revealed that the surface-hydrophobicity values of the films were decreased after the CS-FluTENG and LS-FluTENG experiments due to a roughness increment, and the fibril distance from the nodes was increased. The triboelectric-power density values reached up to 2.15mW/m<SUP>2</SUP> for the CS-FluTENG and 0.8mW/m<SUP>2</SUP> for the LS-FluTENG, respectively. Moreover, the instantaneous power reached up to 2.4 µW for the CS-FluTENG and 1.85 µW for the LS-FluTENG, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel fluid based TENG(FluTENF) using DI water and cPTFE film is proposed. </LI> <LI> Lateral sliding and contact separation type FluTENG is compared and analyzed by FE-SEM analysis. </LI> <LI> The triboelectric power density is achieved upto 2.15mW/m<SUP>2</SUP> for CS-FluTENG and 0.8mW/m<SUP>2</SUP> for LS-FluTENG. </LI> <LI> The energy loss in CS-FluTENG is significantly higher than LS-FluTENG. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P> <B>Scheme1</B>. Schematic illustration of a fluid triboelectric nanogenerator.</P> <P>[DISPLAY OMISSION]</P>

Dry‐Type Artificial Muscles Based on Pendent Sulfonated Chitosan and Functionalized Graphene Oxide for Greatly Enhanced Ionic Interactions and Mechanical Stiffness

Jeon, Jin‐,Han,Cheedarala, Ravi Kumar,Kee, Chang‐,Doo,Oh, Il‐,Kwon WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.48

<P><B>Abstract</B></P><P>Biopolymer‐based artificial muscles are promising candidates for biomedical applications and smart electronic textiles due to their multifaceted advantages like natural abundance, eco‐friendliness, cost‐effectiveness, easy chemical modification and high electical reactivity. However, the biopolymer‐based actuators are showing relatively low actuation performance compared with synthetic electroactive polymers because of inadequate mechanical stiffness, low ionic conductivity and ionic exchange capacity (IEC), and poor durability over long‐term activation. This paper reports a high‐performance electro‐active nano‐biopolymer based on pendent sulfonated chitosan (PSC) and functionalized graphene oxide (GO), exhibiting strong electro‐chemo‐mechanical interations with ionic liquid (IL) in open air environment. The proposed GO‐PSC‐IL nano‐biopolymer membrane shows an icnreased tensile strength and ionic exchange capacity of up to 44.8% and 83.1%, respectively, and increased ionic conductivity of over 18 times, resulting in two times larger bending actuation than the pure chitosan actuator under electrical input signals. Eventually, the GO‐PSC‐IL actuators could show robust and high‐performance actuation even at the very low applied voltages that are required in realistic applications.</P>