Controlling optical gain in semiconducting polymers with nanoscale chain positioning and alignment

Martini, Ignacio B.; Craig, Ian M.; Molenkamp, William C.; Miyata, Hirokatsu; Tolbert, Sarah H.; Schwartz, Benjamin J.

doi:10.1038/nnano.2007.294

Cited by 103 publications

(81 citation statements)

References 28 publications

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“…For example, Miyata and Tolbert et al reported alignment control of semiconducting polymers using uniaxially aligned mesoporous silica films. 25), 26) The semiconducting polymer was well aligned along the uniaxial mesochannels. The polymer/silica composite film showed the polarized absorption and fluorescence caused by aligned polymers.…”

Section: )mentioning

confidence: 99%

Field-Induced alignment controls of one-dimensional mesochannels in mesoporous materials

Yamauchi

2013

J. Ceram. Soc. Japan

147

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Mesoporous materials prepared through the self-assembly of surfactants have attracted wide attention because of their many potential applications. The mesostructural, compositional, and morphological controls of mesoporous materials have been extensively studied thus far. In particular, the macroscopic alignments of one-dimensional (1D) mesochannels and their controls are quite important for the creation of advanced functional materials. In most cases, the direction of mesochannels in mesoporous films lies parallel to the substrate. Vertical orientation of the mesochannels can realize high diffusion and accessibility of guest species from the outside. Here, I review the recent progress on this emerging research field. Various methods have been proposed for the preparation of vertically oriented mesoporous thin films using high magnetic field, shear flow, modification of the substrate, and other methods. I also briefly introduce their applications and a perspective for the future.©2013 The Ceramic Society of Japan. All rights reserved.Key-words : Mesoporous material, Surfactant, Thin film, High magnetic processing [Received April 25, 2013; Accepted June 23, 2013] 1. Mesoporous materials by self-assembly of surfactants Ordered mesoporous materials prepared through 'self-assembly of surfactants' have attracted growing interest due to their special properties, including uniform mesopores (250 nm) and high specific surface areas. 1),2) According to the International Union of Pure and Applied Chemistry (IUPAC), porous materials are classified according to their pore sizes: microporous materials with pore sizes below 2 nm, mesoporous materials with pore sizes between 2 and 50 nm, and macroporous materials with pore sizes exceeding 50 nm.3),4) Zeolites are traditional microporous materials that have been utilized for practical applications in catalysts and adsorbents. Although the microporous materials have high surface areas, due to their small-sized pores, their applications are limited to reactions only for relatively small molecules. Recently, metalorganic frameworks (MOFs) or porous coordination polymers (PCPs) consisting of metal ions coordinated with organic molecules have been extensively studied and used for the storage of gases such as hydrogen and carbon dioxide. 5),6) However, their pore size is still small. In contrast, several types of macroporous materials, such as inverse opal films, track-etched polycarbonate membranes, and porous anodic alumina membranes, have been reported thus far. However, such pore expansion seriously decreases surface area.Unlike other porous materials, mesoporous materials can be easily prepared under a wide range of synthetic conditions. Mesoporous materials exhibit several defined mesostructures, such as lamellar, two-dimensional (2D) hexagonal, three-dimensional (3D) hexagonal, and bicontinuous cubic mesostructures. Furthermore, many framework compositions (e.g., silica, organosilica, metal, and non-siliceous oxides) and various morphologies (e.g., nanoparticle, monolith, a...

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Section: )mentioning

confidence: 99%

Field-Induced alignment controls of one-dimensional mesochannels in mesoporous materials

Yamauchi

2013

J. Ceram. Soc. Japan

147

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“…Mesoporous silica films have potential applications in many fields including sensing [21], catalysis [22], optics [23] and microfluidics [16]. For additional reading, Brinker [10][11] and Grosso [12] provide in-depth and comprehensive reviews on films synthesised via EISA techniques and their potential applications.…”

Section: Templated Mesoporous Thin Filmsmentioning

confidence: 99%

“…One example of the importance of introducing global alignment of nano-channels was documented by Martini et al [23] By confining a semiconductor polymer in a well-aligned 2 D hexagonal mesoporous film (using the rubbing technique) the polymer chains became aligned and exhibited polarised, low-threshold amplified spontaneous emission. In addition, the confined chains behaved as natural waveguides that could be utilised for optical gain requirements.…”

Section: Chemical Epitaxymentioning

confidence: 99%

Self-assembled templates for the generation of arrays of 1-dimensional nanostructures: From molecules to devices

Farrell

Petkov²,

Morris

et al. 2010

Journal of Colloid and Interface Science

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Self-assembled nanoscale porous architectures, such as mesoporous silica films (MPS), block copolymer films (BCP) and porous anodic aluminas (PAAs), are ideal hosts for templating one dimension (1 D) nano-entities for a wide range of electronic, photonic, magnetic and environmental applications. All three templates offer dimensional scalability and tunability over a wide range, with critical pore sizes for each system well below the 20 nm threshold [1][2][3]. Recently, research has progressed towards controlling the pore direction, orientation and long range order of these nanostructures through so called directed self-assembly (DSA). Significantly, the introduction of a wide range of top-down chemically and physically pre-patterning substrates has facilitated the DSA of nanostructures into functional device arrays. The following review begins with an overview of the fundamental aspects of self-assembly and ordering processes during the formation of PAAs, BCPs and MPS films. Special attention is given to the different ways of directing self-assembly, concentrating on properties such as uni-directional alignment, precision placement and registry of the self-assembled structures to hierarchal or top down architectures. Finally, to distinguish this review from other articles we focus on research where nanostructures have been utilised in part to fabricate arrays of functioning devices below the sub 50 nm threshold, by subtractive transfer and additive methods. Where possible, we attempt to compare and contrast the different templating approaches and highlight the strengths and/or limitations that will be important for their potential integration into downstream processes. ACCEPTED MANUSCRIPT 3 SECTION 1.0: SELF ASSEMBLY AND NANO-ARCHITETCURESThe diversity of self-assembled nanostructures and more importantly, their precise orientation within a thin film (fixed to a substrate) ultimately determines their function and overall application. A large population of research reports to date have focused on identifying these orientations and related periodicities, using x-ray and microscopy tools, as well the development of methods for readily manipulating nanostructures, such as pre-patterning of silicon substrates for the alignment of block copolymers (BCPs) [4] and mesoporous thin films (MTFs) [5] and altering the growth direction of porous anodic alumina (PAA) templates [6]. In this section, a brief synopsis of the mechanisms behind the self-assembly/organisation of each system and highlight nanoscale architectures (and orientations), which are important from a device perspective. Templated mesoporous thin filmsOrdered mesoporous powders were first discovered by researchers at the Mobil Petrochemical Corporation in 1992 and shortly after, sol-gel derived mesoporous silica films were fabricated [1,7].The first series of ordered mesoporous films were reported by Yang et al. in 1996 [8], prepared using initial surfactant concentrations above their critical micelle concentration (CMC). However the films prepared fil...

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“…Some reports have also demonstrated much lower thresholds of stimulated emission or amplified spontaneous emission ͑ASE͒ by aligning organic molecules. [3][4][5][6] In this respect, polyfluorenes, such as poly͑9,9-dioctylfluorene͒ ͑F8͒ and poly͑9,9-dioctylfluorene-co-benzothiadiazole͒ ͑F8BT͒, are very attractive materials due to high quantum efficiencies, high optical gain, and good electrical properties.…”

Section: Introductionmentioning

confidence: 99%

Tuning the wavelength of lasing emission in organic semiconducting laser by the orientation of liquid crystalline conjugated polymer

Song

Friend

2008

Journal of Applied Physics

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We report the optical pumping of one-dimensional distributed feedback (DFB) conjugated polymer devices using a uniaxially aligned liquid crystalline polymer, poly(9,9-dioctylfluorene). We can independently select the alignment direction (via a rubbed polyimide layer) and the DFB structure (via nanoimprinting). In comparison with unaligned film, we show that lasing threshold is substantially reduced when absorption is parallel to the aligned direction (∼20.0 μJ cm−2 pulse−1). This is mainly due to the higher absorption coefficient estimated in the table by calculating the exciton densities at each threshold value. We also report the control of lasing wavelength through independent selection of alignment direction and DFB orientation, which is achieved through the control of the effective refractive index of waveguide (neff).

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Controlling optical gain in semiconducting polymers with nanoscale chain positioning and alignment

Cited by 103 publications

References 28 publications

Field-Induced alignment controls of one-dimensional mesochannels in mesoporous materials

Field-Induced alignment controls of one-dimensional mesochannels in mesoporous materials

Self-assembled templates for the generation of arrays of 1-dimensional nanostructures: From molecules to devices

Tuning the wavelength of lasing emission in organic semiconducting laser by the orientation of liquid crystalline conjugated polymer

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