Morphology control of a polythiophene–fullerene bulk heterojunction for enhancement of the high-temperature stability of solar cell performance by a new donor–acceptor diblock copolymer

Lee, Jea Uk,Jung, Jae Woong,Emrick, Todd,Russell, Thomas P,Jo, Won Ho IOP Pub 2010 Nanotechnology Vol.21 No.10

<P>A well defined diblock copolymer (P3HT-<I>b</I>-C<SUB>60</SUB>) based on regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was synthesized via two controlled polymerization steps and used as a compatibilizer for the P3HT/PCBM blend, which has widely been used as an active layer in bulk heterojunction polymer solar cells. The addition of a small amount of P3HT-<I>b</I>-C<SUB>60</SUB> results in not only the reduction of phase size of P3HT/PCBM blend but also the suppression of macrophase separation for long-time thermal annealing owing to the preferential location of the diblock copolymers at the interface between P3HT and PCBM phases. The morphology change with the annealing time is closely related to the change of the power conversion efficiency (PCE) of solar cells: the PCE of P3HT/PCBM greatly decreases with increasing annealing time while the addition of P3HT-<I>b</I>-C<SUB>60</SUB> significantly reduces the decrease of PCE for long-time thermal annealing. </P>

Synthesis of C₆₀-end capped P3HT and its application for high performance of P3HT/PCBM bulk heterojunction solar cells

Lee, Jea Uk,Jung, Jae Woong,Emrick, Todd,Russell, Thomas P.,Jo, Won Ho Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.16

<P>A new C<SUB>60</SUB>-end capped poly(3-hexylthiophene) (P3HT-C<SUB>60</SUB>) was synthesized <I>via</I> a simple three-step process, and used as a compatibilizer for P3HT/PCBM composite for the purpose of controlling the morphology of P3HT/PCBM composite film, and thus improving the long-term thermal stability of solar cell performance. When a small amount of P3HT-C<SUB>60</SUB> was added to P3HT/PCBM, the bicontinuous and nanometre-scale film morphology was developed and preserved for 2 h of annealing at 150 °C. Furthermore, the addition of P3HT-C<SUB>60</SUB> as a compatibilizer suppressed large-scale phase separation of P3HT/PCBM composite even after prolonged annealing time (8 days), and as a result, the P3HT/PCBM/P3HT-C<SUB>60</SUB> bulk heterojunction solar cells exhibited the excellent long-term thermal stability of device performance.</P> <P>Graphic Abstract</P><P>A new C<SUB>60</SUB>-end capped poly(3-hexylthiophene) was synthesized <I>via</I> a simple three-step process, and used as a compatibilizer for P3HT/PCBM composite for the purpose of controlling the morphology of P3HT/PCBM composite film and thus improving the long-term thermal stability of solar cell performance. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b923752f'> </P>

Synthesis and photophysical property of well-defined donor–acceptor diblock copolymer based on regioregular poly(3-hexylthiophene) and fullerene

Lee, Jea Uk,Cirpan, Ali,Emrick, Todd,Russell, Thomas P.,Jo, Won Ho Royal Society of Chemistry 2009 Journal of materials chemistry Vol.19 No.10

<P>A new, well-defined diblock copolymer (P3HT-<I>b</I>-C<SUB>60</SUB>) based on regioregular poly(3-hexylthiophene) (P3HT) and fullerene was synthesized. First, regioregular P3HT was synthesized through Grignard metathesis polymerization, and then methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) were copolymerized by using an end-functionalized P3HT as a macroinitiator for the atom transfer radical polymerization to yield a diblock copolymer (P3HT-<I>b</I>-P(MMA-<I>r</I>-HEMA)). A fullerene derivative functionalized with carboxylic acid, [6,6]-phenyl-C<SUB>61</SUB>-butyric acid (PCBA), was then chemically linked to the HEMA unit in the second block (P(MMA-<I>r</I>-HEMA)) to produce a diblock copolymer with the second block containing fullerenes. Annealing thin films of the copolymer revealed nanometer-scale phase separation, a more suitable morphology for enabling excitons generated in the P3HT domain to more efficiently reach the donor–acceptor interface, relative to simple blends of P3HT and C<SUB>60</SUB>. As a result, photoluminescence of the P3HT-<I>b</I>-C<SUB>60</SUB> diblock copolymer in the films showed a complete quenching of photoluminescence of P3HT, which is indicative of charge transfer between P3HT and fullerene.</P> <P>Graphic Abstract</P><P>A new, well-defined diblock copolymer (P3HT-<I>b</I>-C<SUB>60</SUB>) based on regioregular P3HT and fullerene showed phase separation on a nanometer scale, which allows the excitons generated in the P3HT domain to reach the donor–acceptor interface more efficiently. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b813368a'> </P>

Highly Ordered Nanoporous Template from Triblock Copolymer

Lee, Dong Hyun,Park, Soojin,Gu, Weiyin,Russell, Thomas P. American Chemical Society 2011 ACS NANO Vol.5 No.2

<P>Silica nanoporous templates from poly(1,4-isoprene)-<I>block</I>-polystyrene-<I>block</I>-poly(2-vinyl pyridine) (IS2VP) were prepared. The films of IS2VP spin-coated from toluene showed a dimple-type structure with short-range lateral order. When the films were exposed to a mixed solvent vapor of toluene/hexane, a highly ordered and oriented core−shell structure, consisting of an outer shell of PI, a middle shell of PS, and a core of P2VP, was obtained. The PI was degraded by UV-ozone treatment and removed. A film of polydimethylsiloxane (PDMS) was spin coated onto the remaining film with dimple-type structures and, upon heating, was drawn into the interstitial regions by capillary action. Exposure to oxygen plasma converted the PDMS into silica and degraded all other remaining polymers. This led to highly ordered and oriented nanoporous silica that could be used as an etching mask for transfer of the pattern or templates for metal loading.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-2/nn102832c/production/images/medium/nn-2010-02832c_0009.gif'></P>

Directed Self-Assembly of Asymmetric Block Copolymers in Thin Films Driven by Uniaxially Aligned Topographic Patterns

Lee, Dong-Eun,Ryu, Jaegeon,Hong, Dongki,Park, Soojin,Lee, Dong Hyun,Russell, Thomas P. American Chemical Society 2018 ACS NANO Vol.12 No.2

<P>We present a simple, versatile approach to generate highly ordered nanostructures of block copolymers (BCPs) using rubbed surfaces. A block of poly(tetrafluoroethylene) (PTFE) was dragged across a flat substrate surface above the melting point of PTFE transferring a highly aligned PTFE topographic pattern to the substrate. Si wafer, glass, and polyimide films were used as substrates. Thin films of cylinder-forming asymmetric polystyrene-<I>block</I>-poly(2-vinylpyridine) copolymers (S2VPs) were solvent annealed on the surfaces having the transferred surface pattern to induce their directed self-assembly. Cylinders of P2VP oriented normal to the surface are markedly aligned along the rubbing direction and used as templates to generate extremely uniform arrays of various metallic nanoparticles of gold, silver, and platinum over a large area.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2018/ancac3.2018.12.issue-2/acsnano.7b08226/production/images/medium/nn-2017-08226j_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn7b08226'>ACS Electronic Supporting Info</A></P>

A Simple Route for the Preparation of Mesoporous Nanostructures Using Block Copolymers

Chen, Dian,Park, Soojin,Chen, Jiun-Tai,Redston, Emily,Russell, Thomas P. American Chemical Society 2009 ACS NANO Vol.3 No.9

<P>Poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) nanostructures with multiple morphologies were fabricated by immersing PS-b-P4VP nanotubes in ethylene glycol, a nonsolvent for PS and a good solvent for P4VP, at different temperatures. Mesoporous structures were generated from uniform nanoscopic wormlike micelles due to a solvent-induced reconstruction when the spherical micellar structures were heated above the glass transition temperature of the PS block. The mesoporous nanostructures can be converted into inorganic oxide structures, like SiO(2) and TiO(2), by well-known sol-gel methods. The mesoporous inorganic oxides can be produced with tunable porosity by controlling the molecular weight of the block copolymers. Confinement also plays an important role to create the nanostructures with unusual morphologies.</P>

Directed Self-Assembly of Block Copolymer Thin Films Using Minimal Topographic Patterns

Choi, Jaewon,Huh, June,Carter, Kenneth R.,Russell, Thomas P. American Chemical Society 2016 ACS NANO Vol.10 No.8

<P>We demonstrate that a minimal topographic pattern with a confinement depth (D) much less than the domain spacing of block copolymers (L-0) can be used to achieve highly ordered hexagonal arrays or unidirectionally aligned line patterns over large areas. Cylinder-forming poly(styrene-b-ethylene oxide) (PS-b-PEO) thin films were prepared on a series of minimal single trench patterns with different widths (W) and D. Upon thermal annealing, hexagonal arrays of cylindrical microdomains propagated away from the edges of a single trench, providing insight into the minimum pitch (P) of the trench necessary to fully order hexagonal arrays. The confinement trench D of 0.30L(0), the Win the range of 1.26L(0) to 2.16L(0), and the P as long as 18.84L(0) were found to be effective for the generation of laterally ordered hexagonal arrays with the density amplification up by a factor of 17, within the minimally patterned trench surfaces of 100 mu m by 100 pm. Furthermore, we produced line patterns of cylindrical microdomains by using solvent vapor annealing on the minimally patterned trench surfaces. However, highly aligned line patterns could be achieved only on the patterned surface with P = 5.75L(0), W = 1.264 and D = 030L(0) because the influence of the minimally patterned trench surface on the lateral ordering decreased as the P and W increase at the fixed D, resulting in poor ordering. These findings suggest that the minimal topographic pattern is more effective in guiding hexagonal arrays than in guiding line patterns.</P>

Precise placements of metal nanoparticles from reversible block copolymer nanostructures

Cho, Heesook,Park, Hyungmin,Russell, Thomas P.,Park, Soojin Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.24

<P>We demonstrate the fabrication of reversible block copolymer (BCP) templates that can be used to control the spatial location of metal precursors and nanoparticles. A highly ordered polystyrene-<I>block</I>-poly(2-vinylpyridine) (PS-<I>b</I>-P2VP) micellar array was obtained by solvent annealing. Subsequent immersion of the films in a preferential solvent for the minor component block caused a reorganization of the film to generate a porous structure upon drying. When such reconstructed films were subjected to external stimuli, like solvent vapor or heat, the initial morphology was recovered. These reversible BCP templates were used to control the placement such that, subsequently, oxygen plasma treatment led to the precise placement of metal nanoparticles in a film. By controlling the concentration of the metal precursor solutions, the sizes of the nanoparticles could be tuned.</P> <P>Graphic Abstract</P><P>Stimuli-responsive reversible block copolymer templates were prepared to control the spatial location and size of metal nanoparticles. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm00651c'> </P>

P(S-r-BCB-r-MMA) 게이트 절연체를 이용한 저전압 구동용 펜타센 유기박막트랜지스터

구송희 ( Song Hee Koo ),( Thomas P. Russell ),( Craig J. Hawker ),류두열 ( Du Yeol Ryu ),이화성 ( Hwa Sung Lee ),조정호 ( Jeong Ho Cho ) 한국공업화학회 2011 공업화학 Vol.22 No.5

유기박막트랜지스터 개발의 중요한 이슈 중 하나는 용액 공정이 가능한 저전압구동용 고분자 게이트 절연체의 개발이다. 따라서 본 연구에서는 고성능의 저전압구동이 가능한 유기박막트랜지스터를 위한 우수한 성능의 고분자 게이트 절연체 재료인 poly(styrene-r-benzocyclobutene-r-methyl methacrylate) (P(S-r-BCB-r-MMA))을 합성하였다. P(S-r-BCB-r-MMA)는 경화과정에서 부피의 변화가 거의 없기 때문에 우수한 절연특성을 가지는 매우 얇은 고분자 절연체를 제조할 수 있으며, 이는 주파수에 따른 전기용량 변화를 통해 확인할 수 있다. 펜타센 유기반도체를 기반으로 한 유기박막 트랜지스터 소자를 제작하였을 경우 전계효과이동도 0.25 cm 2 /Vs, 문턱전압 -2 V, 점멸비 ~10 5 , 그리고 sub-threshold swing 400 mV/decade로 우수한 성능을 보인다. 본 연구에서 새롭게 소개된 P(S-r-BCB-r-MMA)는 유연 디스플레이와 같은 미래형 전자소자의 구현을 위한 게이트 절연체 소재로서 하나의 가능성을 제공할 것이다. One of the key issues in the research of organic field-effect transistors (OFETs) is the low-voltage operation. To address this issue, we synthesized poly(styrene-r-benzocyclobutene-r-methyl methacrylate) (P(S-r-BCB-r-MMA)) as a thermally cross-linkable gate dielectrics. The P(S-r-BCB-r-MMA) showed high quality dielectric properties due to the negligible volume change during the cross-linking. The pentacene FETs based on the 34 nm-thick P(S-r-BCB-r-MMA) gate dielectrics operate below 5 V. The P(S-r-BCB-r-MMA) gate dielectrics yielded high device performance, i.e. a field-effect mobility of 0.25 cm 2 /Vs, a threshold voltage of -2 V, an sub-threshold slope of 400 mV/decade, and an on/off current ratio of ~10 5 . The thermally cross-linkable P(S-r-BCB-r-MMA) will provide an attractive candidate for solution-processable gate dielectrics for low-voltage OFETs.

Synthesis of pyridine-capped diketopyrrolopyrrole and its use as a building block of low band-gap polymers for efficient polymer solar cells

Jung, Jae Woong,Liu, Feng,Russell, Thomas P.,Jo, Won Ho The Royal Society of Chemistry 2013 Chemical communications Vol.49 No.76

<P>A new building block for low band-gap polymers, diketopyrrolopyrrole (DPP) flanked by pyridine (PyDPP), has been synthesized <I>via</I> a simple synthetic route. PyDPP was polymerized with bithiophene (BT) to afford a low band-gap copolymer (PBTPyDPP) which was used as an electron donor of the active layer in polymer solar cells. The solar cell device based on PBTPyDPP exhibited a promising PCE of 4.9% with a high <I>V</I><SUB>OC</SUB> over 0.9 V, which is one of the highest values among DPP-based polymer solar cells.</P> <P>Graphic Abstract</P><P>The low band-gap polymers based on diketopyrrolopyrrole flanked by pyridine exhibited a promising PCE of 4.9% with a high <I>V</I><SUB>OC</SUB> over 0.9 V, which is one of the highest values among DPP-based polymer solar cells. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cc44676j'> </P>