Thin Films of Highly Planar Semiconductor Polymers Exhibiting Band-like Transport at Room Temperature

Lee, Jiyoul,Chung, Jong Won,Kim, Do Hwan,Lee, Bang-Lin,Park, Jeong-Il,Lee, Sangyoon,Hä,usermann, Roger,Batlogg, Bertram,Lee, Sang-Soo,Choi, Insil,Kim, Il Won,Kang, Moon Sung American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.25

<P>We report the observation of band-like transport from printed polymer thin films at room temperature. This was achieved from donor-acceptor type thiophene-thiazole copolymer that was carefully designed to enhance the planarity of the backbone and the resulting transfer integral between the macromolecules. Due to the strong molecular interaction, the printed polymer film exhibited extremely low trap density comparable to that of molecular single crystals. Moreover, the energy barrier height for charge transport could be readily reduced with the aid of electric field, which led formation of extended electron states for band-like charge transport at room temperature.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2015/jacsat.2015.137.issue-25/jacs.5b04253/production/images/medium/ja-2015-04253w_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja5b04253'>ACS Electronic Supporting Info</A></P>

Influence of Alkyl Side Chain on the Crystallinity and Trap Density of States in Thiophene and Thiazole Semiconducting Copolymer Based Inkjet-Printed Field-Effect Transistors

Lee, Jiyoul,Chung, Jong Won,Jang, Jaeman,Kim, Do Hwan,Park, Jeong-Il,Lee, Eunkyung,Lee, Bang-Lin,Kim, Joo-Young,Jung, Ji Young,Park, Joon Seok,Koo, Bonwon,Jin, Yong Wan,Kim, Dae Hwan American Chemical Society 2013 Chemistry of materials Vol.25 No.9

<P>The influence of alkyl side chains on the crystallinity of semiconducting copolymer films and their sub-bandgap density-of-states (DOS), the latter being closely related to the stability and the device performance of organic field-effect transistors (OFETs), is investigated. Three different poly(hexathiophene-alt-bithiazole) (PHTBTz) based polymer semiconductors, with identical backbones but different side chain positions and lengths, were synthesized. The crystallinity examined by grazing incidence X-ray diffraction (GIXRD) strongly depends on the number, position, and length of each type of alkyl side chain attached to the thiophene and thiazole copolymer backbones. Also, the sub-bandgap trap DOS distributions were extracted by performing multiple-frequency capacitance–voltage (MF-CV) spectroscopy on the field effect devices. The relationship between film crystallinity and trap DOS in the field-effect transistors can be interpreted in terms of the complex interplay between the number, position, and length of each alkyl side chain for efficient π–π stacking. In particular, the number and position of the alkyl side chain attached to the polymer backbone significantly affects the device performance. Poly(tetryloctylhexathiophene-alt-dioctylbithiazole) (PHTBTz-C8) exhibits the best electrical performance among the different semiconductors synthesized, with a relatively low bulk trap density of ∼2.0 × 10<SUP>20</SUP> cm<SUP>–3</SUP> eV<SUP>–1</SUP> as well as reasonable hole mobility of ∼0.25 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>. The microstructural analyses of this organic material strongly suggest that the short π–π stacking distance induces strong interaction between adjacent polymer backbones, which in turn results in enhanced electrical properties.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2013/cmatex.2013.25.issue-9/cm400592b/production/images/medium/cm-2013-00592b_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm400592b'>ACS Electronic Supporting Info</A></P>

Photoexcited charge collection spectroscopy of two-dimensional polaronic states in polymer thin-film transistors

Lee, Jiyoul,Lee, Bang-Lin,Kim, Jae H.,Lee, Sangyoon,Im, Seongil American Physical Society 2012 Physical review. B, Condensed matter and materials Vol.85 No.4

Organometallic Synthesis of New Soluble,Coplanar Poly(naphthalene-2,6-diyl)-Type pi-Conjugated Polymer,Poly(pyrimido[5,4-d]pyrimidine-2,6-diyl),with Nitrogens Atoms at All of the o-Positions

Bang-lin Lee,Takakazu Yamamoto 한국고분자학회 2002 한국고분자학회 학술대회 연구논문 초록집 Vol.2002 No.4

소셜미디어 이용 동기의 차원 분석과 마케팅 시사점에 관한 탐색적 연구

이방형(Bang Hung Lee),한상린(Seong Keun Yi),이성근(Sang Lin Han),이성훈(Sung Hoon Lee) 한국마케팅학회 2013 마케팅연구 Vol.28 No.2

최근 급속도로 확산되고 있는 소셜미디어는 하나의 단기간의 유행이 아니라 네트웍 시대의 핵심적인 수단이 되고 있다. 특히 마케팅 분야에 있어서의 기업들의 소셜미디어에 대한 관심은 더욱 크다. 그 이유는 텔레비전이나 신문과 같은 전통적인 매체를 통한 광고처럼 일방적인 메시지의 전달에 대하여 소비자들이 더 이상 신뢰하지 않기 때문이다. 따라서 친구나 준거인을 중심으로 하는 소셜미디어의 정보들이 기업들이 발신하는 정보에 비해 더욱 신뢰할 수 있다는 이유 때문에 소셜미디어를 통한 마케팅 활동이 더욱 주목을 받고 있는 것이다. 그러나 소셜미디어가 마케팅의 전략적 도구로 이용되기 위해서는 소셜미디어를 이용하는 이용자들에 대한 보다 정확한 이해가 필요하다. 소셜미디어에 참여하는 이용자들은 대부분 이용동기가 사회적 동기가 강한 것으로 알려져 있다. 이러한 이용자들의 동기에서 추론해 볼 수 있는 것은 이용자들이 이용동기와 관련이 있는 정보에 많은 관심을 가질 것이라는 것이다. 이것은 이용자들의 관심을 끌려는 기업들의 마케팅 노력에 대하여 이용자들은 크게 관심을 두지 않을 가능성이 있다는 것을 의미한다. 따라서 기업들이 소셜미디어를 마케팅에 활용하기 위해서는 이용자들의 이용동기와 이용행태를 파악하여 마케팅전략과 연결하는 과정이 필요할 것이다. 선행연구들은 소셜미디어의 이용동기를 다양한 관점에서 다루고 있지만, 이용동기를 단순히 나열하는 수준으로 그치고 있다. 이러한 이용동기에 관한 선행연구들은 이용동기와 마케팅전략을 연결시키려는 후속연구의 어려움을 만들어 내고 있다. 따라서 소셜미디어의 마케팅 활용과 그에 상응하는 연구가 진행되려면 먼저 소셜미디어의 이용동기를 체계화하는 작업이 필요하다. 이러한 배경 하에서 이 연구는 소셜미디어의 이용동기를 선행연구를 통하여 도출하여 체계적으로 분류해보고, 이러한 이용동기에 관한 체계화를 표적집단토의와 트위터 내용 분석이라는 질적인 연구를 통하여 실증적으로 증명하였다. Recently social media becomes important tool for the communication in the era of network. Especially the interest in the social media gets larger in the field of marketing because social media can be used as a tool of marketing. Furthermore, traditional media such as TV and newspaper become losing the trust because they tend to deliver their message with one directed way. In the contrary, social media is gaining the trust in the delivering message because the friends of the users send the message. But to use the social media as a strategic tool in the marketing, we need to understand why people participate in the social media. That is to say, what motives they have in the use of social media. If we understand the motives of participation, we can use the motives in building the marketing strategy by connecting them to marketing information. So, understanding the users` motive might be a starting point of social media marketing. Former studies listed why users participate in the use of social media. Their studies simply enumerate bits of information. These kinds of former studies have given much difficulties in performing the research on the effective social marketing strategy. Thus the work of organizing the use motives of social media. Under these backgrounds, this study This study tried to organize the motivation of using social media. We divided the user`s motivations into three dimensions such as social motive, functional/ informational motive and hedonic motive through the analyzing the former studies. Additionally we empirically tested the proposed structure of use motives found in the literature review with a qualitative methods such as focus group interview and content analysis in Twitter. In the empirical study, the participants mentioned that their primary motive in the use of social media was to build and keep social relationships, and they did not give much importance to functional and hedonic motive. This study shows that users don`t want marketing activities in the social media, since their primary motivation is social. In the future, this study should expand in the point of methodological view. Since this study used a qualitative method mentioned above, it should be tested by the use of quantitative method with a large sample.

Physical Origins and Analysis of Negative-Bias Stress Instability Mechanism in Polymer-Based Thin-Film Transistors

Jaewook Lee,Jaeman Jang,Hyeongjung Kim,Jiyoul Lee,Bang-Lin Lee,Sung-Jin Choi,Dong Myong Kim,Dae Hwan Kim,Kyung Rok Kim IEEE 2014 IEEE electron device letters Vol.35 No.3

<P>The physical origins of the negative-bias stress (NBS) instability in polymer-based thin-film transistors have been characterized. Through the quantitative analysis by TCAD simulation for the NBS time-dependent experimental results, the threshold voltage (V<SUB>T</SUB>)-shift by sub-bandgap density-of-states redistribution forms 70% and 78% for the measured total V<SUB>T</SUB>-shift while V<SUB>T</SUB>-shift by gate oxide charge trapping only takes 30% and 22% at NBS time of 3000 and 7000 s, respectively. In addition, the increase of source/drain Schottky contact resistance (R<SUB>SD</SUB>) is the main reason for NBS-induced on -current (I<SUB>ON</SUB>) degradation.</P>

Molecular Weight‐Induced Structural Transition of Liquid‐Crystalline Polymer Semiconductor for High‐Stability Organic Transistor

Kim, Do Hwan,Lee, Jiyoul,Park, Jeong‐,Il,Chung, Jong Won,Lee, Wi Hyoung,Giri, Gaurav,Yoo, Byungwook,Koo, Bonwon,Kim, Joo Young,Jin, Yong Wan,Cho, Kilwon,Lee, Bang‐,Lin,Lee, Sangyoon WILEY‐VCH Verlag 2011 Advanced functional materials Vol.21 No.23

<P><B>Abstract</B></P><P>In order to fabricate polymer field‐effect transistors (PFETs) with high electrical stability under bias‐stress, it is crucial to minimize the density of charge trapping sites caused by the disordered regions. Here we report PFETs with excellent electrical stability comparable to that of single‐crystalline organic semiconductors by specifically controlling the molecular weight (MW) of the donor‐acceptor type copolymer semiconductors, poly (didodecylquaterthiophene‐<I>alt</I>‐didodecylbithiazole). We found that MW‐induced thermally structural transition from liquid‐crystalline to semi‐crystalline phases strongly affects the device performance (charge‐carrier mobility and electrical bias‐stability) as well as the nanostructures such as the molecular ordering and the morphological feature. In particular, for the polymer with a MW of 22 kDa, the transfer curves varied little (Δ<I>V</I><SUB>th</SUB> = 3∼4 V) during a period of prolonged bias stress (about 50 000 s) under ambient conditions. This enhancement of the electrical bias‐stability can be attributed to highly ordered liquid‐crystalline nanostructure of copolymer semiconductors on dielectric surface via the optimization of molecular weights.</P>

Design of a Polymer–Carbon Nanohybrid Junction by Interface Modeling for Efficient Printed Transistors

Kim, Do Hwan,Shin, Hyeon-Jin,Lee, Hyo Sug,Lee, Jiyoul,Lee, Bang-Lin,Lee, Wi Hyoung,Lee, Jong-Hwa,Cho, Kilwon,Kim, Woo-Jae,Lee, Sang Yoon,Choi, Jae-Young,Kim, Jong Min American Chemical Society 2012 ACS NANO Vol.6 No.1

<P>Molecularly hybridized materials composed of polymer semiconductors (PSCs) and single-walled carbon nanotubes (SWNTs) may provide a new way to exploit an advantageous combination of semiconductors, which yields electrical properties that are not available in a single-component system. We demonstrate for the first time high-performance inkjet-printed hybrid thin film transistors with an electrically engineered heterostructure by using specially designed PSCs and semiconducting SWNTs (sc-SWNTs) whose system achieved a high mobility of 0.23 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>, no <I>V</I><SUB>on</SUB> shift, and a low off-current. PSCs were designed by calculation of the density of states of the backbone structure, which was related to charge transfer. The sc-SWNTs were prepared by a single cascade of the density-induced separation method. We also revealed that the binding energy between PSCs and sc-SWNTs was strongly affected by the side-chain length of PSCs, leading to the formation of a homogeneous nanohybrid film. The understanding of electrostatic interactions in the heterostructure and experimental results suggests criteria for the design of nanohybrid heterostructures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2012/ancac3.2012.6.issue-1/nn2041472/production/images/medium/nn-2011-041472_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn2041472'>ACS Electronic Supporting Info</A></P>

Dibenzothiopheno[6,5-<i>b</i>:6′,5′-<i>f</i>]thieno[3,2-<i>b</i>]thiophene (DBTTT): High-Performance Small-Molecule Organic Semiconductor for Field-Effect Transistors

Park, Jeong-Il,Chung, Jong Won,Kim, Joo-Young,Lee, Jiyoul,Jung, Ji Young,Koo, Bonwon,Lee, Bang-Lin,Lee, Soon W.,Jin, Yong Wan,Lee, Sang Yoon American Chemical Society 2015 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.137 No.38

<P>We present the synthesis, characterization, and structural analysis of a thiophene-rich heteroacene, dibenzothiopheno[6,5-b:6',5'-f]thieno[3,2-b]thiophene (DBTTT) as well as its application in field-effect transistors. The design of DBTTT is based on the enhancement of intermolecular charge transfer through strong S-S interactions. Crystal structure analysis showed that the intermolecular pi-pi distance is shortened and that the packing density is higher than those of the electronically equivalent benzene analogue, dinaphtho-[2,3-b:2',3'f]thieno[3,2-b]thiophene (DNTT). The highest hole mobility we obtained in polycrystalline DBTTT thin-film transistors was 19.3 cm(2).V-1.s(-1), six times higher than that of DNTT-based transistors. The observed isotropic angular mobilities and thermal stabilities at temperatures up to 140 degrees C indicate the great potential of DBTTT for attaining device uniformity and processability.</P>

Current Trends and Future Research Implications and Directions of Customer Loyalty Programs

Lee.Sung Hoon,Han.Sang-Lin,Lee.Bang Hyung 한국상품학회 2012 商品學硏究 Vol.30 No.6

Customer loyalty programs have influenced a huge impact on firms' customer relationship management strategies. Therefore, it is important for marketing managers to understand how loyalty programs increase customer loyalty and affect firms' profitability. In contrast to the importance of loyalty programs to firms and consumers, there is a lack of understanding and academic research on the effectiveness of loyalty programs. In addition, the research results about the effectiveness and profitability of the programs have suggested conflicting outcomes. To contribute to the resolution of these issues, this paper examines the concepts and related implications of loyalty programs, reviews and analyzes the previous studies to find areas related to future research, and proposes future research implications and directions for loyalty programs. Proposed future research directions are categorized in two main areas: achieving the reliability and validity of the research and expanding the research areas of loyalty programs.