1

Supporting Information

Table of Contents 1. Experimental ......................................................................................................................................... 2

2. Supporting Figures and additional comments .................................................................................. 5

2.1 Supporting comments to the time-resolved PL data in Figure.2 ................................................... 5

2.1.1 Formula for the Förster radius R0................................................................................................ 5

2.2 Supporting Tables: CIE Chromaticity Coordinates of PL and EL spectra in Fig.1 and Fig.3 and photophysical data of the investigated polymers and binary blend....................................................... 6

2.3 Supporting comments to the PL intensity maps in Figure.4 ............................................................ 8

2.4 Supporting Figures 1 and 2: AFM topography images of 8:2 polymer:F8BT blends on ITO/PEDOT.PSS coated substrates(LEDs) ......................................................................................... 9

2.5 Supporting Figure 3: Scanning Near-field Optical Micrographs of 80:20 PFBP.Bn:F8BT and

PFBP.Me⊂β-CD.THS:F8BT blends .................................................................................................. 11

2.6 Supporting Figure 4: AFM topography image of 1:1 PFB.Bn:F8BT blend on Spectrosil............ 12

2.7 Supporting Figure 5 PL decay kinetics of Solvent Vapor Annealed (SVA) film of F8BT:PFBP.Bn

and F8BT:PFBP.Me⊂β-CD.THS 1:1 blends on Spectrosil................................................................. 13

2.7 Supporting Figures 6 ,7,8: µ-Raman analysis of the investigated blends on spectrosil ................ 15

2

1. Experimental

The synthesis of organic-soluble polyfluorene-alt-biphenylene cyclodextrin polyrotaxanes and the

unthreaded analogue was reported elsewhere.1

Poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) was purchased from American Dye Source

(ADS233YE). Solid films (typically 200 nm thick) were spin-coated on Spectrosil® substrates from 2%

bw solutions using chloroform as solvent. The blends were prepared by mixing equal volumes of

solutions of the relative components. The films were deposited at room temperature.

Steady-state photoluminescence measurements were obtained by temporal integration of the

luminescence collected after exciting with a ps-pulsed diode laser (Edinburgh Instruments EPL-375;

100ps FWHM; Eexc=3.3 eV). The detection system included a photomultiplier tube coupled with a

monochromator and time correlated single photon counting unit (Edinburgh Instruments F-900). Time

resolved PL measurements were performed using the second harmonic of a Ti:Sapphire laser at 365 nm

(3.4 eV). Temporal dispersion of the PL signal was achieved with a Hamamatsu C5680 streak camera

with overall time resolution better than 4 ps. The time resolution in the employed experimental

configuration was 7 ps. PL quantum efficiency (ΦPL) measurements on solid films of the pure polymers

and related blends were carried out using a nitrogen saturated integrating sphere and exciting at 3.3 eV

with the same diode laser described above, so as to excite the blue-emitting polymers and at 2.96 eV

within the first absorption band of F8BT. All measurements were performed at room temperature. All

the spectra were corrected for the instrument spectral response. The ET rates from the donors (PFBP.Bn

and PFBP.Me⊂β-CD.THS) to the acceptor (F8BT) were obtained from the PL decay time of the donors,

which depends on both the lifetime of the donors as pure polymers and ET to F8BT.

Light-emitting devices consisted of thin films of PEDOT:PSS spun from water (0.02 g mL-1) solutions

onto pre-patterned, oxygen-plasma-treated ITO substrates2, 3 and annealed at 200°C for 15 minutes in

nitrogen. Then the emissive polymer blend (blending ratio=8:2) was spun from a xylene solution (2 %

by weight) onto the PEDOT:PSS coated substrates in nitrogen. Cathodes consisted of thermally

3

evaporated (at 10-6 mbar) Ca (60 nm) with an Al capping layer (150 nm thickness). Devices were

transferred under nitrogen to a chamber, which was then evacuated to ~10-2 mbar. Basic electrical

characterization involved measuring the device current and light output as a function of the applied

voltage. The current was measured by a Keithley 2400 source meter, which also supplied the voltage.

The luminous output was measured with a calibrated silicon photodiode. The electroluminescence

spectrum was collected with an Andor Newton EMCCD camera coupled with an Andor SHAMROCK

163 spectrograph (bandwidth ~ 4 nm). The current-voltage characteristics of these LEDs were not stable

enough to yield statistically significant device-lifetime data.

Atomic force microscopy (AFM) was performed in tapping mode with a JPK Nanowizard® AFM head

mounted on an Olympus IX71 inverted microscope and using silicon probes with a tip radius of

curvature of <10nm (Mikromasch). Fluorescence images were obtained using Olympus UIS2

Fluorescence mirror units to select the excitation wavelength and emission spectral region: U-MWU2

for the UV excitation (~340-360 nm) and U-MNB2 to excite the samples within the low-energy F8BT

absorption band at ~480 nm.

FLIM images of 512×512 pixels were obtained using a Leica TCS SP2 inverted scanning confocal

microscope coupled with a Becker & Hickl time-correlated single-photon counting (TCSPC) card

SPC830. The second harmonic of a Ti:Sapphire laser at 365 nm (3.40 eV) was used as the excitation

source. Imaging was carried out with a 63× oil-immersion objective (NA = 1.4) and a line scanning

speed of 400 Hz. The refractive index of the immersion oil is 1.518. The emission was collected through

a 525±25 nm band pass filter onto a cooled PMT 100-01 detector (Becker & Hickl, based on a

Hamamatsu H5772P-01 photomultiplier, instrumental response 200 ps). The acquisition time was 100 s

for each image. SPCImage software 2.8 (Becker & Hickl) based on a Levenberg-Marquardt fitting

algorithm was used to fit a single-exponential decay to the fluorescence decay curve in each pixel of the

image, using an instrumental response function generated by the fitting software from the rising edge of

the decay. A false colour scale was assigned to each fluorescence lifetime value (red for a short lifetime

4

and blue for a long lifetime), yielding FLIM maps. The Scanning Near-field Optical Micrographs

(SNOM) were obtained using a Witec Alpha 300 SNOM system with hollow Si-cantilevers. The

samples were excited at 465 nm with an Ar+ laser in order to selectively excite F8BT. The fluorescence

signal was collected by a photomultiplier tube through a long pass filter (edge at 516 nm). Raman

spectra were obtained at 300 K in backscattering configuration by a Labram Dilor spectrometer (He-Ne

laser at 633 nm) with a resolution of about 1 cm−1. Micro-Raman lateral resolution was ~700 nm.

5

2. Supporting Figures and additional comments

2.1 Supporting comments to the time-resolved PL data in Figure.2 of article

In previous works, Bradley et al investigated in details the de-excitation mechanism in polyfluorene

polymer blends (F8:F8BT),4, 5 finding essentially two ET pathways: a fast direct dipole-dipole coupling

and a slower ET channel mediated by exciton diffusion towards the transfer sites, leading to F8 lifetimes

of about 12 ps and 35 ps, respectively. Given the time resolution of our setup (~7 ps) and the different

scope of this letter, we prefer not to read too much into the fast portion of the decay profile of PFBP.Bn

but rather to direct the reader to the existing literature.4, 5

2.1.1 Formula for the Förster radius R0

The Förster radius R0 can be extracted from the overlap integral, J(λ), between the absorption spectrum,

ε(λ), of the acceptor species (A) and the area-normalized fluorescence spectrum, FD(λ), of the donor

species (D).6 If λ is in nanometres and ε(λ) is expressed in units of M-1cm-1, then J(λ) is in units of

M-1 cm-1 (nm)4.

λλλελλ dFJ D∫+∞

=0

4)()()(

The Förster radius R0 in Ångstrom is then,

6 420 )(211.0 λκ JnR DΦ= −

,

Where κ2 is a factor describing the relative orientation in space of the transition dipole moments of the

donor and acceptor (for fast oriented random distributed molecules κ2=2/3), n is the refractive index of

the medium (n=1.7 for both the investigated blends) and ΦD is the quantum efficiency of the donor

luminescence in the absence of the acceptor.

6

2.2 Supporting Tables: CIE Chromaticity Coordinates of PL and EL spectra in Fig.1 and Fig.3 and

photophysical data of the investigated polymers and binary blends.

Supp Table.1 CIE chromaticity coordinates of the PL emission of spin-cast film of the investigated

materials as pure compounds and 1:1 blends and of electroluminescence arising from

Al/Ca/Polymer/PEDOT:PSS/ITO devices incorporating either PFBP.Bn:F8BT or PFBP.Me⊂β-

CD.THS:F8BT 8:2 blends.

CIE Colour Coordinates

Spin-cast Film X Y

PFBP.Me⊂β-CD.THS:F8BT 0.313 0.345

PFBP.Bn:F8BT 0.422 0.522

PFBP.Me⊂β-CD.THS 0.161 0.064

PFBP.Bn 0.159 0.094

F8BT 0.450 0.540

Al/Ca/Polymer/PEDOT:PSS/ITO

PFBP.Me⊂β-CD.THS:F8BT (EL, 8:2 blend)

0.282 0.336

PFBP.Bn:F8BT (EL, 8:2 blend)

0.461 0.533

White Point 1/3 1/3

7

Supp Table.2 Photoluminescence lifetimes and quantum efficiencies (ΦPL) of the investigated

compounds and binary blends. In the table PFBP.Me⊂β-CD.THS is indicated as RX.

PL Lifetime (τTOT)

PL Natural Lifetime (τRAD)

(1) ΦPL

(2)

(%) ΦPL

(3) (%)

ΦPL(4)

(%)

Detection Energy (eV)

2.30 2.96 3.05 2.30 2.96

(PFBP.Bn), 3.05 (RX)

3.25-1.6 2.85 – 1.6 PL intensity

maximum of each compound

Excitation Energy (eV)

3.40 3.40 3.40 3.40 3.40 3.34 2.96 3.40 eV for the PL

lifetime and 3.34 for ΦPL

Emitting species F8BT PFBP.Bn RX F8BT Selectively Whole sample

F8BT Selectively

F8BT 840 ps 1.24 ± 0.13 ns

68 ± 7 67 ± 7

PFBP.Bn 165 ps 500 ± 50 ps 33 ± 4

RX 283 ps 472 ± 48 ps 60 ± 6

PFBP.Bn:F8BT 1.36 ns 33 ps 1.44 ± 0.15 ns

54 ± 6 90 – 100 6.6 ± 7 (PFBP.Bn) 90 - 100 (F8BT)

PFBP.Bn:F8BT (SVA)

1.34 ns 38 ps 1.45 ± 0.15 ns

51 ± 6 90 – 100 7.6 ± 8 (PFBP.Bn)

90 - 100 (F8BT)

RX:F8BT 980 ps 210 ps 1.20 ± 0.13 ns

77 ± 8 82 ± 9 45 ± 5 (RX)

79 ± 9 (F8BT)

RX:F8BT (SVA) 995 ps 221 ps 1.19 ± 0.13 ns

78 ± 9 84 ± 9 47 ± 5 (RX)

81 ± 9 (F8BT)

(1) As extracted from the experimental quantum yields and PL lifetimes according to τRAD= τTOT/ ΦPL

(2) As measured with an integrating sphere (excitation at 371 nm)

(3) As measured with an integrating sphere (excitation at 418 nm)

(4) As extracted from the time-resolved analysis according to ΦBlend=ΦNeat×τBlend/τNeat , in the approximation that

the radiative decay rate kR does not change significantly upon blending

8

2.3 Supporting comments to the PL intensity maps in Figure.4

We observe that the green PL arising from the F8BT-rich phase in Fig.4.f1 is slightly more intense with

respect to the same PL emitted from the PFBP.Bn rich-phase. Previous results by Lidzey et al. on

polyfluorene:F8BT blends spin-coated from toluene solutions7, 8 showed a stronger F8BT PL intensity

arising from the polyfluorene-rich domains, due to the efficient ET to the acceptors that essentially

overcomes the low absorption coefficient of F8BT at the excitation energy of 3.26 eV (380 nm).

Considering the full agreement between our results and the existing literature,9 our data suggest a

different relative concentration of the two phases in our blended films spin-coated from CHCl3

solutions. Such effect is confirmed by micro-Raman scattering measurements (Supp. Fig.6-8) that show

a drastic reduction of F8BT concentration inside the lower phase (PFBP.Bn- rich) that is instead milder

in the PFBP.Me⊂β-CD.THS:F8BT blend.

9

2.4 Supporting Figures 1 and 2: AFM topography images of 8:2 polymer:F8BT blends on

ITO/PEDOT.PSS coated substrates(LEDs)

Supp. Fig.1 Tapping mode AFM images (10×10 µm2) of spin-cast films of F8BT:PFBP.Bn 2:8 blends

on PEDOT.PSS-coated ITO substrates.

Supp. Fig.2 Tapping mode AFM images (10×10 µm2) of spin-cast films of F8BT:PFBP.Me⊂β-CD.THS

on 2:8 blends on PEDOT.PSS-coated ITO substrates.

10

Supp. Figures 1 and 2 show the AFM images of the active layers of the investigated LEDs taken in the

area between the electrodes. A mesoscopic phase separation is clearly observable for the polyrotaxane-

F8BT blend, whereas the reference blend appears essentially homogeneous with about 50 nm size. The

white spots on the films are ascribed to small contaminants such as metal aggregates on the film surface

due to the evaporation of the electrodes.

11

2.5 Supporting Figure 3: Scanning Near-field Optical Micrographs of 80:20 PFBP.Bn:F8BT and

PFBP.Me⊂β-CD.THS:F8BT blends

Supp. Fig. 3 Atomic Force Micrographs and Scanning Near-field Optical Micrographs (marked with x1)

of (a) PFBP.Bn:F8BT (8:2), and (b) and (c) of PFBP.Me⊂β-CD.THS:F8BT (8:2) (collected with a

longpass filter <2.4 eV).

Supporting Figure.3 shows the differences in both surface topography and composition by means of

AFM (NT-MDT Solver in tapping mode) and SNOM imaging respectively for both conventional and

polyrotaxane-based blends. For the conventional blend, the topography is smooth, whereas a significant

phase separation is clearly observable for the polyrotaxane-based blend. As for the PL intensity of F8BT

(PL collected with a longpass filter < 2.4 eV), the emission from F8BT in F8BT:PFBP.Bn blend is

originating from the whole film, whereas for the PFBP.Me⊂β-CD.THS:F8BT, a clear F8BT

concentration gradient is observed between the phase-segregated domains. Interestingly, small F8BT-

rich domains are present inside the polyrotaxane-rich regions, thus suggesting a substantial mixing of

the blend constituents on a smaller lengthscale than our experimental resolution.

12

2.6 Supporting Figure 4: AFM topography image of 1:1 PFB.Bn:F8BT blend on Spectrosil®

Supp. Fig.4 Tapping mode AFM images (10×10 µm2) of as-prepared spin-cast films (not saturated

vapour annealed) of F8BT:PFBP.Bn 1:1 blend on Spectrosil®.

Supp. Figure 4 shows the AFM image of a as-spun film of PFBP.Bn:F8BT blend (1:1) on Spectrosil®

substrate. No mesoscopic separation is observed.

13

2.7 Supporting Figure 5: PL decay kinetics of Solvent Vapour Annealed (SVA) film of F8BT:PFBP.Bn

and F8BT:PFBP.Me⊂β-CD.THS 1:1 blends on Spectrosil®

Supp. Fig.5 PL decay profile of solvent vapor annealed films of (a) PFBP.Bn:F8BT (chloroform, 10

14

minutes) and (b) PFBP.Me⊂β-CD.THS:F8BT (chloroform, 12 hours) 1:1 blends collected at 3.05 eV. c)

Time decay of F8BT PL collected at 2.2 eV in the same SVA blends as in (a) and (b). The single-

exponential fit is reported as red line. Excitation energy, EEXC=3.4 eV.

Supp. Figures 5 shows the PL decay curves of the blue (Supp.Fig.5 a and b, detection energy 2.96 eV

and 3.05 eV for the unthreaded and rotaxinated blend respectively) and the green PL (Supp.Fig.5.c,

detection energy 2.2 eV) arising from solvent vapor annealed films of PFBP.Bn:F8BT and

PFBP.Me⊂β-CD.THS:F8BT 1:1 blends. No significant difference is observed with respect to the PL

kinetics of as-spun films (Figure.2 in the article).

15

2.8 Supporting Figures 6 and 7: µ-Raman analysis of the investigated blends on Spectrosil® substrates

Supp. Fig.6 Raman spectra of spin-cast films of F8BT, PFBP.Bn and PFBP.Me⊂β-CD.THS. Raman

spectra were obtained at 300 K in backscattering configuration by means of an He-Ne laser at 633 nm

with a resolution of about 1 cm−1.

Supp. Fig.7 Micro Raman spectra of spin-cast films of PFBP.Me⊂β CD.THS:F8BT (top panel) and

PFBP.Bn:F8BT 1:1 blends (bottom panel) collected in the phase separated domains. Particular care has

been devoted to assure that the size of the phase separated domain of choice was larger than the probe

laser spot of the Micro-Raman equipment (~700 nm).

16

Supp. Fig. 8 Raman scattering images (30µm×30µm) of (a) PFBP.Bn:F8BT and (b)

PFBP.Me⊂β-CD.THS:F8BT 1:1 (w%) blends mapping the benzothiazole ring stretch peak (1530-1560

cm-1).

Supp. Fig.6 reports the Raman scattering spectra of solid films of the pure polymers. As widely

reported in the literature,7 the fluorene unit stretching gives rise to an intense Raman peak at about 1610

cm-1 which is observable for all three compounds. Furthermore, F8BT displays an intense peak at 1545

cm-1, due to the benzothiazole (BT) ring stretch. This latter phonon mode can be used as a signature for

F8BT in order to map the F8BT concentration throughout the surface of the films of the blends.

As clearly observable in Supp. Fig.7 and Supp. Fig.8, the µ–Raman investigation supports the results

achieved by means of confocal PL and FLIM, showing a much stronger segregation of F8BT in the SVA

blend with unthreaded PFBP.Bn with respect to the polyrotaxane-based blend. The relative intensity of

the Raman peak at 1546 cm-1 (BT signature) with respect to the polyfluorene stretching signal at 1602-

1609 cm-1 is much stronger for the PFBP.Me⊂β-CD.THS:F8BT than for the conventional blend, thus

confirming that the concentration gradient is larger in the latter.

17

Supplementary References

1. Frampton, M. J.; Sforazzini, G.; Brovelli, S.; Latini, G.; Townsend, E.; Williams, C. C.; Charas, A.; Zalewski, L.; Kaka, N. S.; Sirish, M.; Parrott, L. J.; Wilson, J. S.; Cacialli, F.; Anderson, H. L. Adv. Funct. Mater. 2008, 18, 3367-3376.

2. Kim, J. S.; Cacialli, F.; Granström, M.; Friend, R. H.; Johansson, N.; Salaneck, W. R.; Daik, R.; Feast, W. J. Synth. Met. 1999, 101, (1-3), 111-112.

3. Kim, J.-S.; Cacialli, F.; Friend, R. Thin Solid Films 2003, 445, (2), 358-366. 4. Buckley, A. R.; Rahn, M. D.; Hill, J.; Cabanillas-Gonzalez, J.; Fox, A. M.; Bradley, D. D. C.

Chem. Phys. Lett. 2001, 339, (5-6), 331-336. 5. Hill, J.; Heriot, S. Y.; Worsfold, O.; Richardson, T. H.; Fox, A. M.; Bradley, D. D. C. Synth.

Met. 2003, 139, (3), 787-790. 6. Lakowicz, J. R., Principles of Fluorescence Spectroscopy. Second ed.; Springer: New York,

1986; p 368-388. 7. Cadby, A.; Dean, R.; Jones, R. A. L.; Lidzey, D. G. Adv. Mat. 2006, 18, (20), 2713-2719. 8. Cadby, A. J.; Dean, R.; Elliott, C.; Jones, R. A. L.; Fox, A. M.; Lidzey, D. G. Adv. Mat. 2007,

19, (1), 107-111. 9. Moons, E. J. Phys.: Condens. Matter 2002, 14, (47), 12235-12260.