Supplementary Materials for

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1 advances.sciencemag.org/cgi/content/full/1/11/e /dc1 Supplementary Materials for All-polymeric control of nanoferronics Beibei Xu, Huashan Li, Asha Hall, Wenxiu Gao, Maogang Gong, Guoliang Yuan, Jeffrey Grossman, Shenqiang Ren The PDF file includes: Published 18 December 2015, Sci. Adv. 1, e (2015) DOI: /sciadv Mass transport induced crystallization of CTCCs Fig. S1. Photograph of the crystals. Fig. S2. Optical microscopy image of the initial growth stage of the crystals. Fig. S3. Dark-field optical microscopy image of the CTCC. Fig. S4. AFM image near the center of the cocrystals. Classical molecule dynamics (MD) simulations on the interface configuration of polythiophene/c60 CTCCs Fig. S5. Polythiophene/C60 interface configuration while polythiophene structure starts from free surface at x direction. Fig. S6. Polythiophene/C60 interface configuration with monolayer or singlemolecule polythiophene. Table S1. Energy-level distribution of polythiophene layer close to the polythiophene/c60 interface with multilayer polythiophene crystal and single molecule, respectively. Time- and RR-dependent crystallization Fig. S7. Time-dependent crystal growing for 91% RR CTCC. Fig. S8. Time-dependent crystal growing for 95.7% RR CTCC. Absorption spectra Fig. S9. Absorption spectra of CTCCs measured by microscope in the range of 600 to 1200 nm. RR-dependent electrical and magnetic properties Fig. S10. Magnetoconductance. Fig. S11. ME coupling effect with different loading electric field. Electrical properties Fig. S12. Electrical properties as a function of temperature and frequency. Anisotropic MC effect

2 Fig. S13. MC of CTCC under different electric field. Fig. S14. MC of CTCC under different magnetic field. Fig. S15. Light-illuminated MC of CTCC under different magnetic field. Fig. S16. Light intensity dependent MC of vertical. Piezoelectric response Fig. S17. Amplitude of the piezoelectric response versus tip bias. Electron spin resonance Fig. S18. ESR of CTCC at 80 K and room temperature. Angle-dependent magnetism Fig. S19. Angle-dependent M-H loops of CTCC. M-H loop of CTCC powder Fig. S20. M-H loop of the free-standing CTCC powder. Dark and light-illuminated magnetism Fig. S21 Magnetoelectric coupling Fig. S22. Tunability of magnetization by electric field when the electric field is oriented perpendicular (A and C) and parallel (B and D) to the cocrystal long axis without (A and B) and with (C and D) light illumination. References (43 55)

3 1) Mass transport induced crystallization of CTCCs Figure S1 Photograph of the crystals. A, The conventional method prepared materials. B, The synthesized crystals studied here. In the high concentration of solution, mass depletion among the nuclei leads to the preferential growth of the co-crystals from initial contact line of the solution towards the mass transportation direction (the center) as shown in fig. S2.

4 Figure S2 Optical microscopy image of the initial growth stage of the crystals. A, B, Bright-field and dark-field image of the crystals, 8 minutes after the drop-casting. C, D, Bright-field and dark-field image of the crystals, 20 minutes after the drop-casting. The scale bar is 100 μm. The high solvent vapor pressure decreases the evaporation rate of the solvent, inducing the effective self-assembly into uniform and long co-crystals (fig. S3). Obvious phase separation between thiophene donor and fullerene acceptor can be found on the images indicating the segregated stack structure of the CTCCs. Figure S3 Dark-field optical microscopy image of the CTCC. The scale bar is 20 μm. Atomic force microscope (AFM) image (fig. S4) is taken near the center of the crystal also reveals the surface separation of the co-crystal.

5 Figure S4 A-D, High resolution TEM images of CTCCs. E-F, AFM image near the center of the cocrystals.

6 2) Classical molecule dynamics (MD) simulations on the interface configuration of polythiophene/c60 CTCCs The interface between P3HT and C60 are of significant importance which will not only influence the crystal structure but also the corresponding properties. Some factors will determine the interface framework, that is the interfacial ordering (roughness) and the number of molecules, the distance from the interface. In order to explore the interfacial effects on charge transport of segregated stacked CTCC superstructures, we utilize classical molecular dynamics (MD) and density functional theory (DFT) to investigate the interfacial ordering between P3HT and C60 crystal phases, and its influences on electrical properties of the polymer. While the {111} direction of C60 fcc crystal is aligned to the direction of the polymer chain as suggested by experimental measurements, there exists a rotational degree of freedom, and thus we admit that the two configurations used in our simulations are not the only possibilities in reality. The particular configurations were chosen to represent situations with distinct roughness, and to enable the matching of periodicity between the P3HT and C60 phase with a sufficiently small simulation cell. We carried out classical molecule dynamics (MD) simulations with the LAMMPS package.(43) The force field described by Cheung et al. was used to account for both the intramolecular and the intermolecular polythiophene-polythiophene interactions.(44) Harmonic potentials were adopted for bond stretching and angle bending, with the force constants given by the MM3 force field.(45) Lennard- Jones potential was employed for the van der Waals interactions, with the parameters found from the OPLS parameter set.(46) While most of the torsion parameters were obtained from the MM3 force field(45) the inter-ring torsion potential was derived from ab initio calculations (MP2/aug-cc-pVTZ) on 2-2-bithiophene.(47) The C60 molecules were modeled as ridge and uncharged Lennard-Jones particles, with parameters found to reproduce C60 crystal properties.(48, 49), The AMBER99 force field(50) was employed to describe the interaction between the P3HT and the C60 molecules, which have been successfully implemented in P3HT/SWNT system to predict π-π stacking forces.(51) All cutoffs of nonbonded terms were set to 12 Å. Simulations were first performed separately on P3HT and C60 crystals in the constant-npt ensemble until the density reached convergence. The Nose-Hoover thermostat at 300 K and anisotropic barostat at 1 atm (52) were implemented with relaxation times of 0.1 and 0.5 ps respectively. Then the interface configurations were generated by connecting the P3HT and the C60 phases in the x direction with a spacing of 1.0 Å. Finally, simulations on the combined systems were performed in the constant-nvt ensemble for 1 ns with a 0.5 fs time step. With the structures obtained by MD simulation, we performed ab-initio calculations for a set of

7 singe P3HT molecules with the SIESTA (v3.2) package.(53) The relativistic Troullier-Martins pseudopotentials with nonlinear core corrections(54) were used. In order to reproduce electrical structures obtained by the plane-wave method, we employed polarized triple-ζ (TZP) basis sets for C and H atoms as the localized numerical atomic orbitals, while a polarized double-ζ (DZP) basis set(55) for S atoms. The side chains of each sample were replaced by methyl passivation. This is justified by a test calculation on a prototype molecule containing 3 unit cells of P3HT, which HOMO/LUMO level shifts from -3.87/-2.37 ev with the entire side chains, to -3.90/-2.40 ev with two C atoms in each side chain, to -3.94/-2.42 ev with only one C atom in each side chain. Figure S5 Polythiophene/C60 interface configuration while polythiophene structure starts from free surface at x direction. A, B, The configuration consists of 24 polythiophene molecules and 216 C60 molecules with rough surface at t = 0 ns and 1 ns, respectively. C, D, The configuration consists of 56 polythiophene molecules and 288 C60 molecules with flat surface at t = 0 ns and 1 ns, respectively. The disorder at monolayer polythiophene/c60 crystal increases noticeably, while a single polythiophene molecule could be distorted substantially to completely adapt to the C60 surface even when the surface roughness is large. In case of a single polythiophene molecule attached to C60 surface, the irregular structure of polythiophene leads to localization of wavefunction, and thus a much larger band gap (fig. S6, tab. S1).

8 Figure S6 Polythiophene/C60 interface configuration with monolayer or single-molecule polythiophene. Table S1 Energy-level distribution of polythiophene layer close to the polythiophene/c60 interface with multilayer polythiophene crystal and single molecule, respectively. Layer 4 is the layer closest to the polythiophene/c60 interface. Only one molecule is selected in each layer. configuration 1 configuration 2 HOMO (ev) LUMO (ev) gap (ev) HOMO (ev) LUMO (ev) gap (ev) layer layer layer layer single molecule ) Time- and RR-dependent crystallization The transportation and optical properties of polythiophene polymer films can be improved with the

9 increase of the degree of RR of polythiophene molecules.(32) To verify the influence of RR on our CTCCs, we measured the time and RR dependent crystallization here (fig. S8 and S9). The starting seed crystal materials are important for the growth of large sized crystals. Moreover, from the photograph, we can find that the dimension and density for HRR CTCCs is larger than that of the LRR CTCCs. Figure S7 Time-dependent crystal growing for 91% RR CTCC. The scale bar is 100 μm.

10 Figure S8 Time-dependent crystal growing for 95.7% RR CTCC. The scale bar is 100 μm. 4) Absorption spectra The sample was mounted on an Olympus IX71 inverted microscope equipped with a 20X objective. The absorption spectra was obtained using a Princeton Instruments IsoPlane SCT 320 equipped with a ProEM 1600 electron multiplying CCD camera which presents more details on the absorption in the range of 600~1200 nm.

11 Figure S9 Absorption spectra of CTCCs measured by microscope in the range of 600 to 1200 nm. 5) RR-dependent electrical and magnetic properties RR will also influence on electric and magnetic properties. While loading magnetic field, the current density for both LRR and HRR decreases (fig. S10A, B), resulting in negative magnetoconductance ( MC [ J(B) J(0)]/ J(B), where J (B) and J(0) are the current density with and without loading magnetic field). The HRR film has a larger MC than that of the LRR film (fig. S10C). The applied magnetic field will reduce the spin mixing, leading to the increase of triplet charge transfer with the decrease of singlet charge transfer through intersystem crossing.(37) The lifetime of triplet charge transfer is much longer than that of singlet charge transfer. Then the triplet charge transfer could partly be translated into triplet excitons. The reaction between triplet excitons and free charge carriers will decrease the mobility of free charge carriers, resulting in the decrease of the current density with the loading of magnetic field and leading to negative MC. Figure S10 Magnetoconductance (MC). A-B, HRR and LRR films under different electric field, respectively. C, Comparison of electric field intensity dependent MC for HRR and LRR films.

12 We also find that magnetoelectric (ME) coupling coefficient for the HRR co-crystal is larger than that of the LRR co-crystal. (fig. S11). The coupling between the charge-density wave and spin-density wave leads to the exciton magnetism. The loading of electric field modulates the charge-density wave leading to the change of spin-density wave which enhances the magnetism. Figure S11 ME coupling effect with different loading electric field. A-B, HRR and LRR films, respectively. C, Comparison of electric field intensity dependent ME coupling coefficiency for HRR and LRR films. HRR leads to the closer and more ordered packing of the stacking structure of CTCCs, so in the following we focus on the properties of HRR CTCCs. 6) Electrical properties The temperature dependent conductivity and loss tangent (fig. S12A and D) shows pronounced transition peak above room temperature, indicating the potential phase transition in the CTCC cocrystals above room temperature. In fig. S12B, at high temperature and low frequency (< 10 Hz), the conductivity keeps constant, closing to the dc conductivity. With the increase of frequency, the conductivity is nearly linear. Due to dielectric relaxation, the permittivity decrease with the increase of frequency at all the temperatures (fig. S12C). The loss tangent decrease with the increase of frequency,

13 which is inconsistent to that of the permittivity (fig. S12D). There are two peaks in both the temperature dependent conductivity and loss tangent, indicating the phase separation of polythiophene and C60 in the segregated stacking CTCCs. Figure S12 Electrical properties as a function of temperature and frequency. A, Temperature dependent conductivity for the selected frequencies of CTCCs. B, Frequency dependent conductivity for the selected temperature of CTCCs. C, Frequency dependent permittivity for the selected temperature of CTCCs. D, Temperature dependent loss tangent for the selected frequencies of CTCCs. 7) Anisotropic MC effect When the electric field is oriented parallel to the co-crystal long axis, MC value is more obvious than that perpendicular to the co-crystal long axis, although the electric field for the parallel direction is much smaller (fig. S13). The large difference originates from the anisotropic charge carrier density. The co-crystal long axis is the π-π stacking direction of thiophene molecule with larger charge carrier density than other packing directions.

14 Figure S13 MC of CTCC under different electric field. A-D, The electric field is oriented perpendicular to the co-crystal long axis. E-G, The electric field is oriented parallel to the co-crystal long axis. Figure S14 and fig. S15 compares the dark and light illuminated MC. With the increase of the applied magnetic field intensity, both dark and light illuminated MC increase. Moreover, the light illuminated MC has a much larger value due to the photoexcitation induced charge transfer.

15 Figure S14 MC of CTCC under different magnetic field. The electric field is 13KV/cm. The electric field is oriented perpendicular to the co-crystal long axis. Figure S15 Light-illuminated MC of CTCC under different magnetic field. The electric field is oriented perpendicular to the co-crystal long axis. The electric field is 13KV/cm. The light intensity is 70 mw/cm 2. Figure S16 demonstrates light intensity dependent MC. With the increase of light intensity from 0 to 70 mw/cm 2, negative MC effect increase all the way. The increased light intensity will induce more charge carriers and charge transfer, leading to the increased scattering interaction between free charge carriers and triplet excitons, which will decrease the charge carrier mobility. So the negative MC increases. Then, when the light intensity is increased to 110 mw/cm 2, the negative MC effect becomes positive. At a high light intensity, the free charge carriers could have enough energy to collide and dissociate triplet excitons into free charge carriers leading to the increase of the current density. Further

16 increase of the light intensity to 130 mw/cm 2, part of the charge transfer states will be dissociated, then the corresponding number of generated free charge carriers and triplet excitions from the conversion of charge transfer will decrease leading to the decrease of positive MC effect. Figure S16 Light intensity dependent MC of vertical. The electric field is oriented perpendicular to the co-crystal long axis. The electric field is 13KV/cm, the magnetic field intensity is 1500 Oe. 8) Piezoelectric response Figure S17 Amplitude of the piezoelectric response versus tip bias.

17 9) Electron spin resonance (ESR) ESR measured at 80 K and room temperature demonstrates the existence of charge transfer in the CTCCs (fig. S18). The signal at 80 K is stronger than that at room temperature implying that low temperature is beneficial for the generation of charge transfer. Figure S18 ESR of CTCC at 80 K and room temperature. 10) Angle-dependent magnetism Magnetic hysteresis (M-H) loop under different angle of magnetic field are used to illustrate the anisotropic magnetism of the CTCCs. When the magnetic is applied in-plane to the CTCCs, the angle is set as 0 o, and 90 o is for the magnetic field out-of-plane (fig. S19).

18 Figure S19 Angle-dependent M-H loops of CTCC. 11) M-H loop of CTCC powder The M-H loop was measured at room temperature, suggesting possible ferromagnetism of the CTCCs (fig. S20). Figure S20 M-H loop of the free standing CTCC powder.

19 12) Dark and light-illuminated magnetism The M-H loop and electron spin resonance (ESR) were used to elucidate the magnetism of the CTCCs (fig. S21). Compared with the dark condition, light illumination increases both the magnetism and susceptibility. As discussed above, photoexcitation induce more charge carriers in the CTCCs, leading to the increase of charge transfer. The charge transfer can dissociate into polarons, corresponding to the increase of the ESR signal. In addition, the coupling between the charge-density wave and spin-density wave leads to the exciton magnetism. Photoexcitation could modulate the chargedensity wave leading to the change of spin-density wave, which enhances the magnetism. Figure S21 A, Dark and light illuminated M-H loops. B, Dark and light illuminated ESR signals measured at 80 K. 13) Magnetoelectric coupling The electric field tunable magnetization value taken near the coervity field (Hc = 56 Oe) for both direction increases with the increase of the applied electric field and light illumination intensity (fig. S22). Moreover, the parallel direction shows larger coupling coefficient than that of the perpendicular direction even though the loading electric field for this direction is much smaller, indicating the large anisotropy in the CTCCs.

20 Figure S22 Tunability of magnetization by electric field when the electric field is oriented perpendicular (A and C) and parallel (B and D) to the cocrystal long axis without (A and B) and with (C and D) light illumination.