Electronic Supplementary Data

Molecular Weight Effect on Surface and Bulk Structure of

Poly(3-hexylthiophene) Thin Films

Takuya Matsumoto, Keishirou Nishi, Shunsuke Tamba, Masaru Kotera, Chizuru Hongo,

Atsunori Mori, Takashi Nishino*

Department of Chemical Science and Engineering, Graduate School of Engineering,

Kobe University Rokko, Nada, Kobe, 657-8501, Japan

S1

abun

danc

e 00.

10.

20.

30.

4

X : parts per Million : Proton

12.0 11.0 10.0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0 -1.0 -2.0

7.

286

7.

248

7.

041

6.

970

2.

811

2.

793

2.

776

2.

703

2.

602

2.

584

2.

565

2.

547

1.

696

1.

679

1.

620

1.

599

1.

579

1.

563

1.

428

1.

343

1.

335

1.

207

1.

187

0.

903

6.00

3.02

2.07

1.93

1.00

76.1

6m

Figure S1. 1H NMR spectrum of P3HT in CDCl3.

S2

Figure S2. XPS wide spectrum of (top) and photograph of water droplet on (bottom) (a) piranha treated silicon wafer and (b) silane coupling treated silicon wafer.

S3

Figure S3. X-ray reflectivity profiles of P3HT thin films with different molecular weight, spin-coated on piranha treated silicon wafers.

S4

Figure S4. Relationship between the incident angle α and the X-ray penetration depth of X-ray

beams for P3HT film.

Penetration depth of X-ray beam. The penetration depth of X-ray beams was defined

as the depth where the intensity was reduced to 1/e times. The critical angle αc was

presented by the following equations:

α c=√2 δ (2)

δ=(λ2r e N )

2 π (3)

where λ was a wavelength of X-ray beam (λ = 1.548 Å), re was a classical electron

radius (2.82 10−13 cm), N was a mole electron density.

In the case of P3HT, form the equation (2), (3),

N=90 ×0.00825 ×6.02 ×1023=3.59 ×1023(cm−3)

δ=3.83 ×10−6

S5

α c=2.77 ×10−3(rad )=0.15 9(deg .)

In α > αc, the penetration depth labs was estimated from the following equation:

l|¿|=sin α

μ¿ (4)

μ=ρ [ ω1 μ1+ω2 μ2+⋯ ] (5)

where μ was a linear absorption coefficient, ρ was the density, ωi was a mass fraction of

each element and μi was mass absorption coefficient.

In the case of α < αc, the penetration depth ltot was estimated from the following

equation:

ltot=1

2 k √αc2−α 2 (6)

In Figure S4 in the supporting information, the penetration depth of X-ray beam for

P3HT was shown.

S6

Figure S5. Schematic diagrams of the X-ray diffractometer for small angle incidence X-ray diffraction.

S7

Figure S6. Crystal structure of P3HT.[S1][1]

Figure S7. X-ray diffraction profile of P3HT powder annealed at 100 °C for 1 hour.

S8

Table S3. Relationship between rotation speed while spin-coating and thickness of P3HT thin films.

Rotation speed Thicknessa

rpm nm

0 100000

500 70

1000 60

2000 50

3000 70

4000 30

5000 30a Measured by AFM height images.

S9

Figure S8. “Out-of-plane” X-ray diffraction profiles of P3HT (Mw = 13k) thin films with various incidence angles (α = 0.20°(a), 0.15°(b), 0.10°(c), 0.08°(d)) on the piranha (dashed lines) and silane coupling (solid lines) treated silicon wafers.

Figure S9. “Out-of-plane” X-ray diffraction profiles of P3HT (Mw = 828k) thin films with various incidence angles (α = 0.20°(a), 0.15°(b), 0.10°(c), 0.08°(d)) on the piranha (dashed lines) and silane coupling (solid lines) treated silicon wafers.

S10

Figure S10. Two-dimentional GIXD of high molecular weight P3HT (Mw = 828k). X-ray beam energy was 10 keV, incidence angle α was 0.16°.

S11

REFERENCES

[S1] T.J. Prosa, M.J. Winokur, J. Moulton, P. Smith, A.J. Heeger, X-ray structural studies of poly(3-alkylthiophenes): an example of an inverse comb, Macromolecules 25 (1992) 4364–4372. doi:10.1021/ma00043a019.

S12