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Dutta, Gitish K.,Han, A‐,Reum,Lee, Junghoon,Kim, Yiho,Oh, Joon Hak,Yang, Changduk WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.42
<P><B>Abstract</B></P><P>Systematic creation of polymeric semiconductors from novel building blocks is critical for improving charge transport properties in organic field‐effect transistors (OFETs). A series of ultralow‐bandgap polymers containing thienoisoindigo (TIIG) as a thiophene analogue of isoindigo (IIG) is synthesized. The UV‐Vis absorptions of the TIIG‐based polymers (<B>PTIIG‐T</B>, <B>PTIIG‐Se</B>, and <B>PTIIG‐DT</B>) exhibit broad bands covering the visible to near‐infrared range of up to 1600 nm. All the polymers exhibit unipolar p‐channel operations with regard to gold contacts. <B>PTIIG‐DT</B> with centrosymmetric donor exhibits a maximum mobility of 0.20 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> under gold contacts, which is higher than those of the other polymers containing axisymmetric donors. Intriguingly, OFETs fabricated with aluminum electrodes show ambipolar charge transport with hole and electron mobilities of up to 0.28 (<B>PTIIG‐DT</B>) and 0.03 (<B>PTIIG‐T</B>) cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively. This is a record value for the hitherto reported TIIG‐based OFETs. The finding demonstrates that TIIG‐based polymers can potentially function as either unipolar or ambipolar semiconductors without reliance on the degree of electron affinity of the co‐monomers.</P>
한아름,( Gitish K. Dutta ),이정훈,이해랑,이상면,안형주,신태주,양창덕,오준학 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
In molecular design of high performance polymer semiconductors, side-chain engineering has recently attracted great attentions due to easy modulation of intermolecular self-assembly and charge-carrier mobility. Inspired by the side-chain effects on the intrinsic properties of polymer semiconductors, herein we report a systematic investigation of the diketopyrrolopyrrole (DPP)-based π-systems incorporating novel ε-branched side chains. The developed polymers exhibited extraordinarily high electrical performance with both hole and electron mobilities superior to that of unipolar amorphous silicon.
Kang, So-Huei,Lee, Hae Rang,Dutta, Gitish K.,Lee, Junghoon,Oh, Joon Hak,Yang, Changduk American Chemical Society 2017 Macromolecules Vol.50 No.3
<P>The pi-extended (E)-2-(2-(thiophen-2-ye-vinyl)thiophene (TVT)-based polymers are an interesting class of semiconducting polymers because of their excellent mobilities and unique film microstructures. Despite these properties, the effect of the side-chain regiochemistry of TVT skeletons on the intrinsic properties of these polymers remains unclear. To investigate this, in this study, hexyl-substituted TVT subunits with a 'tail in (TI)' or 'tail out (TO)' regiosymmetrical arrangement were first introduced into diketo-pyrrolopyrrole (DPP) -based copolymer main chains to afford 'isomeric' polymers PI and PO, respectively. By combining optical spectroscopy, atomic force microscopy (AFM), and grazing incidence X-ray diffraction (GIXD) data, we quantitatively characterized the aggregation, crystallization, and backbone orientation of both polymer films, which were then correlated to the charge carrier mobilities. The PI film exhibited a bimodal packing motif comprising a mixture of edge-on and face-on orientations, which was beneficial for three-dimensional (3D) charge transport and resulted in a hole mobility 2-fold larger than that in the PO film (mu(h) = 1.69 cm(2) V-1 s(-1)). This comparative study substantiates the important role of the regiochemistry of TVT in developing high-performance semiconducting polymers.</P>
Kim, Jonggi,Yun, Myoung Hee,Kim, Gi-Hwan,Lee, Jungho,Lee, Sang Myeon,Ko, Seo-Jin,Kim, Yiho,Dutta, Gitish K.,Moon, Mijin,Park, Song Yi,Kim, Dong Suk,Kim, Jin Young,Yang, Changduk American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.10
<P>The introduction of fluorine (F) atoms onto conjugated polymer backbone has verified to be an effective way to enhance the overall performance of polymer-based bulk-heterojunction (BHJ) solar cells, but the underlying working principles are not yet fully uncovered. As our attempt to further understand the impact of F, herein we have reported two novel fluorinated analogues of PCDTBT, namely, <B>PCDTFBT</B> (1F) and <B>PCDT2FBT</B> (2F), through inclusion of either one or two F atoms into the benzothiadiazole (BT) unit of the polymer backbone and the characterization of their physical properties, especially their performance in solar cells. Together with a profound effect of fluorination on the optical property, nature of charge transport, and molecular organization, F atoms are effective in lowering both the HOMO and LUMO levels of the polymers without a large change in the energy bandgaps. <B>PCDTFBT</B>-based BHJ solar cell shows a power conversion efficiency (PCE) of 3.96 % with high open-circuit voltage (<I>V</I><SUB>OC</SUB>) of 0.95 V, mainly due to the deep HOMO level (−5.54 eV). To the best of our knowledge, the resulting <I>V</I><SUB>OC</SUB> is comparable to the record <I>V</I><SUB>OC</SUB> values in single junction devices. Furthermore, to our delight, the best <B>PCDTFBT</B>-based device, prepared using 2 % v/v diphenyl ether (DPE) additive, reaches the PCE of 4.29 %. On the other hand, doubly-fluorinated polymer <B>PCDT2FBT</B> shows the only moderate PCE of 2.07 % with a decrease in <I>V</I><SUB>OC</SUB> (0.88 V), in spite of the further lowering of the HOMO level (−5.67 eV) with raising the number of F atoms. Thus, our results highlight that an improvement in efficiency by tuning the energy levels of the polymers by means of molecular design can be expected only if their truly optimized morphologies with fullerene in BHJ systems are materialized.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-10/am500891z/production/images/medium/am-2014-00891z_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am500891z'>ACS Electronic Supporting Info</A></P>