b S Supporting Information ' INTRODUCTION Regioregular poly(3-alkylthiophenes) (P3HT) have attracted extensive scientific interest due to their superior charge-transporting characteristics and favorable processability for optoelectronic device applications, such as photovoltaic cells (PV) 1À4 and organic field-effect transistor (OFET). 5À9 Aligned one-dimensional (1D) structure with nanometer-sized confinement would significantly enhance the orientation of P3HT crystals, which is more favorable for its anisotropic charge transport than the unaligned 1D structure. The charge-carrier mobility of P3HT OFET could be manipulated over a wide range of 4 Â 10 À4 to 3 Â 10 À2 cm 2 /V 3 s through different nanostructure or orientation on crystal domains, such as nanofibers. 10À15 P3HT nanofibers were generally produced via solution selfassembly 11,12 or electrospinning (ES). 13À15 We are particularly interested in producing polymer nanofibers through the ES process because it has the advantages of low cost, flexible morphology tuning, and high-throughput continuous production. 16À20 The strong stretching force and the geometrical confinement associated with the ES process could induce the orientation of polymer chains along the long axis of fiber, 21À23 whose photoelectronic properties were different from that in the spin-coated films. 24À31 In addition, ES aligned nanofibers were easily prepared from several approaches, 32À38 including a scanning tip, 32 a drum rotating at a high speed, 33 a rotating wheel-like bobbin, 34 collector/electrode modification, 22,35,36 and magnetic field-assistance. 37 Liu et al. prepared single P3HT ES nanofiber-based OFET with the mobility as high as 0.03 cm 2 /V 3 s. 14 However, droplets and beaded P3HT nanofibers were occasionally formed due to the rapid evaporation of the solvent and low polymer solubility. Recently, Lee et al. used the coaxial setup to produce continuous and uniform P3HT ES nanofibers with the carrier mobility of 0.017 cm 2 /V 3 s, by continuously providing solvent in the shell to prevent the phase separation of P3HT from the solution at the end

While ordered bicontinuous double diamond (OBDD) in block copolymers has always been considered as an unstable structure relative to ordered bicontinuous double gyroid (OBDG), here we report the existence of a thermodynamically stable OBDD structure in a diblock copolymer composed of a stereoregular block. A slightly asymmetric syndiotactic polypropylene-block-polystyrene (sPP-b-PS) as cast from xylene was found to display the OBDD morphology. When the OBDD-forming diblock was heated, this structure transformed to the OBDG phase at ca. 155 °C. Interestingly, OBDD was recovered upon cooling even in the temperature range above melting point of sPP, indicating that OBDD was a thermodynamically stable structure for sPP-b-PS melt, which was in contradiction to the conventional view. We propose that the larger free energy cost encountered in OBDD due to the larger packing frustration may be compensated sufficiently by the release of free energy due to local packing of the conformationally ordered segments of sPP blocks, which stabilizes the OBDD structure at the lower temperatures.

All conjugated C60-containing block copolymers (BCPs) based on quasi-living Grignard metathesis (GRIM) polymerization have been designed and synthesized for application in polymer solar cells (PSCs). The C60-containing BCP can induce the formation of a self-organization nanostructure of P3HT domain. Moreover, this C60-containing BCP serves as a compatibilizer to reduce the interfacial tension between the P3HT and C60, thus help establishing a moderate phase-separated morphology with crystalline P3HT and C60 domain. The performance up to 2.56%(AM 1.5G irradiation (100 mW/cm2)) of a P3HT:C60 device can be achieved by using C60–BCP as additive without any post-treatment.

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Blending with a homopolymer is an effective approach to tailor the microphase-separated morphology of block copolymers. It has been established for the blends of coil−coil diblock copolymer (A-b-B) with the corresponding homopolymer (h-A) that h-A can be solubilized uniformly into A mcirodomain to induce structure transformation when its molecular weight is smaller than that of the A block, i.e., α = M h-A /M b-A < 1. Here we examine if the microdomain structure of a rod−coil diblock copolymer, poly(2,5-diethylhexyloxy-1,4phenylenevinylene)-block-poly(methyl methacrylate) (DEH-PPV-b-PMMA), may be systematically tuned by blending with PMMA hompolymer (h-PMMA). The blends over the major composition window were found to undergo macrophase separation even when the value of α was as low as 0.3. The phase separation led to the formation of a copolymer-rich phase and a homopolymer-rich phase, in which microphase separation occurred, yielding a well-ordered lamellar structure and a sponge structure, respectively. The phase behavior of the blend of rod− coil diblock with the corresponding coil homopolymer is hence fundamentally different from that of the conventional blend of coil−coil diblock in that microdomain morphology transformation induced by completely uniform solublization of coil homopolymer into the selective microdomain is essentially inaccessible. This fact is attributed to the large positive free energy of mixing between the whole rod−coil diblock and the coil homopolymer due to strong rod−rod attraction, the intrinsically strong repulsion between DEH-PPV and PMMA, and the low entropy of mixing.