Control of all‐conjugated block copolymer crystallization via thermal and solvent annealing

Abstract

Control of the crystallization of conjugated polymers is of critical importance to the performance of organic electronics, such as organic photovoltaic devices, due to the effect on charge separation and transport, particularly for allpolymer devices. The block copolymer poly(3-dodecylthiophene)-block-poly(9,9-dioctylfluorene) (P3DDT-b-PF), which has matched crystallization temperatures for each block, is used to study the effects of processing history on resulting crystallization. For longer annealing times and rapid quenching to room temperature, P3DDT crystals are preferred whereas for shorter annealing times and slower quenching, PF crystals are preferred. Both crystal forms are evidenced for long annealing time and slow quenching. Additionally, for room temperature annealing in the presence of a chloroform vapor, PF crystals are found in the PF b phase with the predominant crystal peak oriented perpendicular to the thermally annealed case. These results will provide guidance for optimizing annealing strategies for future donor/acceptor block copolymer photovoltaic devices. V C 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 900-906

Direct visualization of microphase separation in block copoly(3-alkylthiophene)s

“…The increased control over the polymerization allows for a much better control over the molecular and, also, supramolecular structure. 13,[24][25][26][27][28] Applied to block copolymers with sufficiently differing blocks, this can result in a control over the microscopic morphology which is created by the microphases of the constituting blocks. In turn, a thermodynamically stable morphology can signicantly enhance the performance and lifetime of e.g.…”

“…These techniques give insight into different aspects of the morphology of the polymers. The X-ray diffraction techniques such as (Grazing Incidence) Wide Angle X-ray Scattering ((GI)WAXS), 24,26,30,31 Wide Angle X-ray Diffraction (WAXD), 27,31 Small Angle X-ray Scattering (SAXS) 31 and X-ray diffraction (XRD) 28,31,32 can identify the presence of different crystalline microphases by correlating the different observed refraction signals with the different microphases and these refraction signals also give insight in the lattices and stacking distances. The obtained stacking distances can this way directly be correlated with the different microphases that are present.…”

“…Also Differential Scanning Calorimetry (DSC) measurements are frequently used to conrm the presence of separate microphases. 24,[26][27][28]31,32 This is oen reected in the presence of different melting peaks, that are normally ascribed to different microphases in the block copolymer, with their own semi-crystallinity. 24,31,32 Nevertheless, these techniques do not provide an actual visualization of the phase separation.…”

Impact of Competing Crystallization Processes on the Structure of All-Conjugated Donor–Acceptor Block Copolymers P3HT-b-PNDIT2 in Highly Oriented Thin Films

“…24 The sequential crystallization of two conjugated blocks has been investigated with conjugated BCPs made of poly(dioctylfluorene) and P3HT, but the relative packing of the two blocks and their mutual influence on crystallization was not assessed. 25,26 Even more appealing are BCPs based on P3HT and the n- of P3HT-b-PNDIT2 in thin films was investigated using GIWAXS. [27][28][29] These studies demonstrated that both blocks can crystallize such that P3HT orients preferentially edge-on whereas PNDIT2 orients rather face-on on the substrate.…”

Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

“…The assembly of nanostructured materials designed for specific functions is of increasing interest for a broad variety of applications as nanoparticles typically display extreme performances when measured on the microscopic scale. Hybrid nano-devices [1][2][3] are becoming ubiquitous in a vast range of applications, such as organic transistors, 4,5 organic solar cells, 6,7 and artificial photosynthetic systems. [8][9][10] The key advantage of combining nanostructured materials and conventional electronic platforms is that the nanomaterials respond in a very specific manner to external stimuli (e.g., the change of optical and electronic structure as a response to light or varying temperature).…”