Synthesis of PCDTBT-Based Fluorinated Polymers for High Open-Circuit Voltage in Organic Photovoltaics: Towards an Understanding of Relationships between Polymer Energy Levels Engineering and Ideal Morphology Control

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>

Easily Attainable Phenothiazine-BasedPolymers forPolymer Solar Cells: Advantage of Insertion of <i>S</i>,<i>S</i>-dioxides into its Polymer for Inverted Structure SolarCells

Kim, Gyoungsik,Yeom, Hye Rim,Cho, Shinuk,Seo, Jung Hwa,Kim, Jin Young,Yang, Changduk American ChemicalSociety 2012 Macromolecules Vol.45 No.4

<P>Two donor– (D−) acceptor (A) type polymersbasedon a soluble chromophore of phenothiazine (PT) unit that is a tricyclicnitrogen–sulfur heterocycle, have been synthesized by introducingan electron-deficient benzothiadiazole (BT) building block copolymerizedwith either PT or phenothiazine-<I>S</I>,<I>S</I>-dioxide (PT-<I>SS</I>) unit as an oxidized form of PT.The resulting polymers, <B>PPTDTBT</B> and <B>PPTDTBT-</B><I><B>SS</B></I> are fully characterized by UV–visabsorption, electrochemical cyclic voltammetry, X-ray diffraction(XRD), and DFT theoretical calculations. We find that the maximumabsorption of <B>PPTDTBT</B> is not only markedly red-shiftedwith respect to that of <B>PPTDTBT-</B><I><B>SS</B></I> but also its band gap as well as molecular energy levelsare readily tuned by the insertion of <I>S</I>,<I>S</I>-dioxides into the polymer. The main interest is focused on the electronicapplications of the two polymers in organic field-effect transistors(OFETs) as well as conventional and inverted polymeric solar cells(PSCs). <B>PPTDTBT</B> is a typical p-type polymer semiconductorfor OFETs and conventional PSCs based on this polymer and PC<SUB>71</SUB>BM show a power conversion efficiency (PCE) of 1.69%. In case of <B>PPTDTBT-</B><I><B>SS</B></I>, the devices characteristicsresult in: (i) 1 order of magnitude higher hole mobility (μ= 6.9 × 10<SUP>–4</SUP> cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>) than that obtained with <B>PPTDTBT</B> and (ii) improved performance of the inverted PSCs (1.22%), comparedto its conventional devices. Such positive features can be accountedfor in terms of closer packing molecular characteristics owing eitherto the effects of dipolar intermolecular interactions orientated fromthe sulfonyl groups or the relatively high coplanarity of <B>PPTDTBT-</B><I><B>SS</B></I> backbone.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2012/mamobx.2012.45.issue-4/ma202661b/production/images/medium/ma-2011-02661b_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma202661b'>ACS Electronic Supporting Info</A></P>

A synthetic approach to a fullerene-rich dendron and its linear polymer <i>via</i> ring-opening metathesis polymerization

Kim, Jonggi,Yun, Myoung Hee,Lee, Junghoon,Kim, Jin Young,Wudl, Fred,Yang, Changduk Royal Society of Chemistry 2011 Chemical communications Vol.47 No.11

<P>Through the esterification of an acyl chloride functionalized fullerene precursor with dendritic alcohol, a fullerene-rich dendron containing a norbornene unit at the focal point is prepared for ring-opening metathesis polymerization to obtain its linear polymer with a unimodal and narrow molar mass distribution (PDI = 1.08) by a progressive addition of catalysts.</P> <P>Graphic Abstract</P><P>A platform for a fullerene-rich linear polymer is established through ROMP and a controlled methodology of addition of catalyst. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0cc05470d'> </P>

Ambipolar Semiconducting Polymers with <i>π-</i>Spacer Linked Bis-Benzothiadiazole Blocks as Strong Accepting Units

Kim, Jonggi,Han, A-Reum,Hong, Jayeon,Kim, Gyoungsik,Lee, Junghoon,Shin, Tae Joo,Oh, Joon Hak,Yang, Changduk American Chemical Society 2014 Chemistry of materials Vol.26 No.17

<P>Recognizing the importance of molecular coplanarity and with the aim of developing new, ideal strong acceptor-building units in semiconducting polymers for high-performance organic electronics, herein we present a simplified single-step synthesis of novel vinylene- and acetylene-linked bis-benzothiadiazole (<B>VBBT</B> and <B>ABBT</B>) monomers with enlarged planarity relative to a conventionally used acceptor, benzothiadiazole (BT). Along these lines, four polymers (<B>PDPP-VBBT</B>, <B>PDPP-ABBT</B>, <B>PIID-VBBT</B>, and <B>PIID-ABBT</B>) incorporating either <B>VBBT</B> or <B>ABBT</B> moieties are synthesized by copolymerizing with centro-symmetric ketopyrrole cores, such as diketopyrrolopyrrole (DPP) and isoindigo (IID), and their electronic, physical, and transistor properties are studied. These polymers show relatively balanced ambipolar transport, and <B>PDPP-VBBT</B> yields hole and electron mobilities as high as 0.32 and 0.13 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>, respectively. Interestingly, the acetylenic linkages lead to enhanced electron transportation in ketopyrrole-based polymers, showing a decreased threshold voltage and inverting voltage in the transistor and inverter devices, respectively. The IID-based BBT polymers exhibit the inversion of the dominant polarity depending on the type of unsaturated carbon bridge. Owing to their strong electron-accepting ability and their highly π-extended and planar structures, <B>VBBT</B> and <B>ABBT</B> monomers should be extended to the rational design of high-performance polymers in the field of organic electronics.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2014/cmatex.2014.26.issue-17/cm500800u/production/images/medium/cm-2014-00800u_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm500800u'>ACS Electronic Supporting Info</A></P>

Control of Charge Dynamics via Use of Nonionic Phosphonate Chains and Their Effectiveness for Inverted Structure Solar Cells

Kim, Gyoungsik,Song, Seyeong,Lee, Jungho,Kim, Taehyo,Lee, Tack Ho,Walker, Bright,Kim, Jin Young,Yang, Changduk Wiley Blackwell (John Wiley Sons) 2015 ADVANCED ENERGY MATERIALS Vol.5 No.18

High-efficiency polymer solar cells with a cost-effective quinoxaline polymer through nanoscale morphology control induced by practical processing additives

Kim, Yiho,Yeom, Hye Rim,Kim, Jin Young,Yang, Changduk The Royal Society of Chemistry 2013 Energy & environmental science Vol.6 No.6

<P>In the quest to improve the performance of polymer solar cells (PSCs) with a view to realizing economic viability, various solvent additives such as 1,8-octanedithiol (ODT), 1,8-diiodooctane (DIO), diphenylether (DPE) and 1-chloronaphthalene (CN) are used in easily obtainable poly(2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-dyl-<I>alt</I>-thiophene-2,5-diyl) (TQ1)-based systems with [6,6]-phenyl C<SUB>71</SUB>-butyric acid methyl ester (PC<SUB>71</SUB>BM) as an acceptor to optimize the active layer nanomorphology. Utilizing a combination of X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM), we find that the addition of 5% (v/v) CN leads to smoother films, less heterogeneous surface features, and well-distributed TQ1:PC<SUB>71</SUB>BM phases, resulting in more balanced charge transport in the devices and a highly efficient power conversion efficiency (PCE) of 7.08%. This is a record for quinoxaline-based PCSs and is also comparable with the hitherto reported highest efficiency of the PSCs in single junction devices. In addition, the PSCs using an inverted device structure show a satisfactory PCE of 5.83% with high stability to ambient exposure, maintaining over 80% of its initial PCE, even after storage in air for more than 1 month.</P> <P>Graphic Abstract</P><P>Upon adding CN, cost-effective quinoxaline (TQ1)-based polymer solar cells afford a high efficiency of 7.08%. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3ee00110e'> </P>

A Balanced Face-On to Edge-On Texture Ratio in Naphthalene Diimide-Based Polymers with Hybrid Siloxane Chains Directs Highly Efficient Electron Transport

Kim, Yiho,Long, Dang Xuan,Lee, Junghoon,Kim, Gyoungsik,Shin, Tae Joo,Nam, Kyung-Wan,Noh, Yong-Young,Yang, Changduk American Chemical Society 2015 Macromolecules Vol.48 No.15

<P>Structure–property relationships associated with a hybrid siloxane-terminated hexyl chain (SiC6), photophysics, molecular packing, thin-film morphology, and charge carrier transport are reported for two novel naphthalene diimide (NDI)-based polymers; P(NDI2SiC6-T2) consists of NDI and bithiophene (T2) repeating units, while for P(NDI2SiC6-TVT), the (<I>E</I>)-2-(2-(thiophen-2-yl)-vinyl)thiophene (TVT) units are introduced into the NDI-based backbone. The analysis of the optical spectra shows that the preaggregation of these polymers in solution is highly sensitive to the choice of solvent such that the films prepared by using different solvents can be “tuned” with regard to their degrees and types of the aggregates. In-depth morphology investigations (atomic force microscopy (AFM), grazing incidence X-ray diffraction (GIXD), and near-edge X-ray absorption fine structure (NEXAFS)) combined with device optimization studies are used to probe the interplay between molecular structure, molecular packing, and OFET mobility. It is found that the polymer films cast as a coating from chloroform (CF) solvent favor a mixed face-on and edge-on orientation, while 1-chloronaphthalene (CN)-cast films favor an almost entirely edge-on orientation, resulting in a difference in mobility between CF- and CN-cast devices. Within this work, the annealed P(NDI2SiC6-T2) device fabricated from CF, despite showing a less densely packed organization, shows the highest electron mobility of up to 1.04 cm<SUP>2</SUP>/V·s due to a highly balanced face-on to edge-on ratio. This work, for the first time, advances our understanding for how the balanced face-on to edge-on ratio plays a dramatic role in facilitating charge transport, opening a new charge-transport mechanism in electronic devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2015/mamobx.2015.48.issue-15/acs.macromol.5b01012/production/images/medium/ma-2015-01012k_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma5b01012'>ACS Electronic Supporting Info</A></P>

터보프롭 엔진의 온라인 상태감시 프로그램 개발에 관한 연구

공창덕(Changduk Kong),김건우(Keonwoo Kim),임세명(Semyung Lim),김지현(Jihyun Kim) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.5

항공기 추진시스템에 있어 내구성과 신뢰성을 향상과 운용비용 절감을 위한 상태감시 및 진단 시스템의 개발 및 적용이 일반화되고 있다. 특히 40,000ft 이상의 고고도에서 장시간 운용되는 무인항공기를 신뢰성 있게 운용하기 위해서는 열악한 환경에서 작동되는 추진시스템의 손상이나 성능저하에 대한 사전 대처를 위한 상태감시 시스템이 필수적으로 요구된다. 이에 본 연구에서는 MATLAB/SIMULINK를 이용하여 온라인 상태감시 프로그램을 제안하였다. 입력 모듈에서 현 개발단계에서는 실제 엔진 계측신호가 유용하지 않아 이를 모사하였다. 제안된 온라인 상태감시 모니터링 프로그램은 적용 가능성을 확인하기 위해 실제 터보프롭 엔진에 적용하였다. Recently, development and application of the condition monitoring and diagnostic system for improvement of durability and reliability and reduction of operating cost is generalized in the aircraft propulsion system. Especially, for reliable operation of the UAV which is flying in high altitude more than 40,000 ft for a long time an condition monitoring system to identify faults and degradations of its propulsion system should be needed. Therefore, this work proposes an on-line condition monitoring program using MATLAB/SIMULINK. In the development phase of the program, a engine signal generation module is used to simulate real engine measuring parameters instead of the real engine. The proposed on-line condition monitoring program was applied to a real turboprop engine to validate its application capability.

소형 가스터빈 엔진 실험 데이터를 이용한 역모델링 연구

공창덕(Changduk Kong),임세명(Semyeong Lim),구영주(Youngju Koo),김건우(Keonwoo Kim),오성환(Seonghwan Oh),김지현(Jihyun Kim) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.11

가스터빈 엔진의 성능은 그 구성품 성능 특성에 큰 영향을 받는다. 보통 이러한 구성품 성능 특성은 여러 조건에서의 수많은 실험을 통해 얻을 수 있지만 그것은 제작사의 고유 재산이기 때문에 쉽게 제공되지 않는다. 그렇기 때문에 보통 성능 덱을 이용하거나 소유하고 있는 엔진 성능 맵을 스케일링 하여 사용한다. 하지만 이러한 방법은 탈설계점에서 오차를 보인다. 이에 본 연구에서는 소형 가스터빈 엔진 실험 장치를 구성하여 몇 구간에서의 실험을 통해 데이터를 축적하고 이를 이용하여 구성품 성능 맵을 축척하는 방법을 제시하였다. 그리고 프로그램을 이용하여 대상 엔진의 정상상태 성능 모델을 구성하여 실제 측정 데이터와 새롭게 생성된 구성품 맵을 사용했을 경우, 그리고 기존의 방법을 이용한 경우를 비교하였다. The gas turbine engine performance is greatly relied on its component performance characteristics. Generally, acquisition of component maps is not easy for engine purchasers because it is an expensive intellectual property of gas turbine engine supplier. In the previous work, the maps were inversely generated from engine performance deck data, but this method is limited to obtain the realistic maps due to calculated performance deck data. Therefore this work proposes newly to generate more realistic compressor map from experimental performance test data. And then a realistic compressor map can be generated form those processed data using the proposed extended scaling method at each rotational speed. Evaluation can be made through comparison between performance analysis results using the performance simulation program including the generated compressor map and on-condition monitoring performance data.

[권하는 책] From the Ground Up - The Business of Building in the Age of Money

김창덕(Kim Changduk) 대한건축학회 2003 建築 Vol.47 No.10