Supporting Information

� Wiley-VCH 2013

69451 Weinheim, Germany

Doping of Organic Semiconductors: Impact of Dopant Strength andElectronic Coupling**Henry M�ndez, Georg Heimel,* Andreas Opitz, Katrein Sauer, Patrick Barkowski,Martin Oehzelt, Junshi Soeda, Toshihiro Okamoto, Jun Takeya, Jean-Baptiste Arlin, Jean-Yves Balandier, Yves Geerts, Norbert Koch, and Ingo Salzmann*

ange_201302396_sm_miscellaneous_information.pdf

CONTENTS

I. Experimental Details S2

II. Chemical Structures of the Compounds S2

III. X-ray Diffraction Reciprocal Space Maps S3

A. 1:1 Mixed Films of (1) and (2d) S3

B. 1:1 Mixed Films of (1) with (2a-d) and (3) S4

IV. Dopant Electron Affinities S5

V. Huckel-like Treatment of the Energy Levels of the Complexes S6

VI. Supporting UV-VIS Absorption Data S7

A. Optical Absorption Spectroscopy on (1) Doped with (2a-c) and (3) S7

B. Schematic Energy Level Diagrams S8

C. Optical Absorption Spectroscopy on the Ionized Dopants (2a-d) S9

VII. Single Crystal Solution of the (1)-(2a-d) Mixed Crystals S10

A. Crystal data S10

B. Structure refinement S11

References S12

S1

I. EXPERIMENTAL DETAILS

Compound (1) [1] was synthesized at the Laboratory of Polymer Chemistry (Free University of

Brussels). (3) was received from Novaled AG (Dresden, Germany), (2a-d) were purchased from

TCI Europe. Mother solutions of the host [0.5 mg/ml] and acceptor molecules [0.20-0.28 mg/ml]

were obtained using chloroform as solvent (Aldrich, HPLC type with purity > 99.9%). A series

of mixed solutions at different OSC/dopant ratios was prepared. Drop-cast and spin-coated films

(10 Hz) were prepared on SiOx substrates (Siegert prime grade, native oxide, used as received) for

structural analysis (XRD) and on QX-type quartz (Prazisions Glas & Optik GmbH, Germany)

for UV-VIS (Perkin-Elmer Lambda 900 spectrometer). The conductivity was measured between

interdigitated indium tin oxide contacts with a Keithley SourceMeter 2400, and film thickness was

measured with a Dektak II (Veeco GmbH) profilometer. All processing was done under N2 at-

mosphere (Glovebox by Braun GmbH, O2< 0.1 ppm, H2O< 0.1 ppm). XRD and grazing-incidence

XRD were carried out at the beamline W1 at DESY-HASYLAB (hν= 10.5 KeV) using a MYTHEN

1D detector. Single-crystal diffraction was carried out on (1)/(2a-d) mixed single crystals grown

from chloroform solution (for details see Sec. VII). DFT calculations (6-31G** basis set) on iso-

lated molecules and complexes employed the long-range corrected ωB97X-D exchange-correlation

functional for full geometry optimization, as it contains semi-empirical van der Waals corrections

[2], and the PBE0 hybrid functional [3] to subsequently compute molecular orbitals (isosurfaces

drawn at an isovalue of 0.01 a−30 ), their energies, and optical transitions with TDDFT.

II. CHEMICAL STRUCTURES OF THE COMPOUNDS

S

S

H21C10

C10H21

Y X

ZX

CN

CNNC

NC

CN

CNNC

NC FFF

FF F

1

2a : X,Y,Z = H2b : X,Y = H; Z = F2c : X = H; Y,Z = F2d : X,Y,Z = F3

(d) (e)

FIG. S1. Chemical structures of 1: 2,7-didecyl-[1]benzothieno[3,2-b][1]benzothiophene (C10BTBT), 2a:

tetracyanoquinodimethane (TCNQ), its derivatives with increasing fluorination 2b: FTCNQ, 2c: F2TCNQ,

2d: F4TCNQ, and 3: 2,2’-(perfluoronaphtalene 2,6-diylidene)dimalononitrile (F6TCNNQ).

S2

III. X-RAY DIFFRACTION RECIPROCAL SPACE MAPS

A. 1:1 Mixed Films of (1) and (2d)

q z / Å-1

qxy / Å-11.0 2.01.5 2.5 3.0 3.5

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

FIG. S2. Grazing-incidence x-ray diffraction (GIXRD) reciprocal space map of a 1:1 mixed film of (1)

and (2d) processed via drop-casting from CHCl3 solution on native SiOx under N2 atmosphere. The

map is indexed with triclinic unit-cell parameters of the single crystal solution: a= 7.0715 A, b= 8.0773 A,

c= 19.8477 A, α= 97.718 ◦, β= 94.049 ◦, and γ= 107.845 ◦. The incident angle of the primary beam

(10.5 keV) was set to αi = 0.15◦. Colors correspond to diffraction intensities in logarithmic scale, circle

areas to calculated structure factors; qxy and qz denote the in-plane and out-of-plane components of the

scattering vector.

S3

B. 1:1 Mixed Films of (1) with (2a-d) and (3)q z / Å

-1

qxy / Å-1

0.8 1.21.0 1.4 1.6 1.8 2.0 2.2

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

q z / Å-1

qxy / Å-1

0.8 1.21.0 1.4 1.6 1.8 2.0 2.2

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

q z / Å-1

qxy / Å-1

0.8 1.21.0 1.4 1.6 1.8 2.0 2.2

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

q z / Å-1

qxy / Å-1

0.8 1.21.0 1.4 1.6 1.8 2.0 2.2

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

q z / Å-1

qxy / Å-1

0.8 1.21.0 1.4 1.6 1.8 2.0 2.2

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

q z / Å-1

qxy / Å-1

0.8 1.21.0 1.4 1.6 1.8 2.0 2.2

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

pure (1) spincoated (1) + (2a) dropcast

(1) + (2c) dropcast

(1) + (3) dropcast

(1) + (2a) spincoated

(1) + (2d) spincoated

(a)

(c)

(e)

(b)

(d)

(f)

FIG. S3. GIXRD reciprocal space map of spincoated (left) and dropcast (right) films of (a) pure (1),

1:1 mixed films with (b-c) (2a), (d) (2c), (e) (2d), and (f) (3) on SiOx substrates; unit cells from single-

crystal diffraction are listed in Fig. 2c of the main text and Tab. S2. For (3), no single-crystal solution is

available and unit-cell determination from GIXRD was impossible due to the low intensity of the diffraction

features [see peaks in the left corner of (f) marked with arrows]. Colors correspond to diffraction intensities

in logarithmic scale; features of pure (1) are marked with red circles, circle areas correspond to structure

factors; qxy and qz denote the in-plane and out-of-plane components of the scattering vector.

S4

IV. DOPANT ELECTRON AFFINITIES

0 1 2 3 4 56.0

5.5

5.0

4.5

4.0

Ene

rgy

w.r.

tEva

c/e

V

number of fluorine (x)

IE of (1)

Number of fluorines

Ene

rgy

from

Eva

c

4.0

4.5

5.0

5.5

6.00 1 2 3 4 6

(a) (b)

(2a) (2b) (2c) (2d) (3)

(F3)

(1)

FIG. S4. (a) DFT-calculated energies of the lowest unoccupied molecular orbitals (open squares) and

experimental [4] (filled squares) electron affinities (EA) of the dopants (2a-d, 3) used within this work

and that of the additional dopant (F3) [that is (2a) with three fluorine substitutions] plotted against the

number of fluorines. The dashed line indicates the DFT-calculated HOMO energy of (1). (b) DFT-calculated

isosurface plots (isovalue 0.01 a−30 ) of the HOMO of (1) and the respective LUMOs of the dopants.

2a 2b F3 2c 2d 3

EAexp 4.23 4.55 n/a 4.59 5.08 n/a

EL 4.69 4.81 4.91 5.02 5.13 5.17

T1 1.66 1.57 n/a 1.50 1.34 1.29

T2 2.20 2.11 n/a 2.05 1.88 1.85

β 0.43 0.56 n/a 0.53 0.61 0.59

TABLE S1. Experimental [4] electron affinities (EAexp) and DFT-calculated LUMO energies (EL) of the

dopants from Fig. S1 (in eV) and that of (2a) with three fluorine substitutions [labelled as (F3)]. T1 and

T2 denote the energies of the optical transitions taken from Fig. 3b of the main text; β is the value of the

resonance integral extracted from: the respective EAexp values from Ref. 4, the DFT-calculated HOMO

energy of (1) as an approximation for its IE, and the experimentally determined optical gaps (T1) of the

complexes; see caption of Fig. S5 for details on a Huckel-like treatment yielding β.

S5

V. HUCKEL-LIKE TREATMENT OF THE ENERGY LEVELS OF THE COMPLEXES

5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 4.06.5

6.0

5.5

5.0

4.5

4.0

3.5

Cal

c.en

ergy

leve

lsof

com

plex

/eV

EA of p-dopant / eV

β = 0.55 eV

EA

= IE

Complex

HOsc

EVac

T1

IEEA

vari

able

2a 2b

2c 2d

3

1

2a-d, 3

LHyb

HHyb

LAcc

HHyb

LHyb

FIG. S5. Energy levels of the complexes formed between (1) and all dopants [(2a-d) and (3)] as modelled

by a Huckel-like treatment [5] (solid curve) using the minimal basis set of the two frontier molecular orbitals

(that is HOsc, the HOMO of (1), and LAcc, the LUMO of the dopants). The eigenvalues of the Hamiltonian

satisfy the secular equation E1/2 = 1/2[(HOsc + LAcc)±√

(HOsc − LAcc)2 + 4β2], where the two solutions

E1/2 are the energies of HHyb and LHyb, respectively, and β is the resonance integral; energy values for

HOsc and LAcc as depicted in Fig. S7; β set constant to 0.55 eV. The respective optical gaps (deduced from

from transition T1 in Fig. 3b of the main text) are indicated as vertical lines. For the hypothetic case of EA

being equal to 5.65 eV [that is the IE of (1)] a finite gap remains. Note that by this treatment the exciton

binding energy is not taken into account. It is assumed constant for all complexes and is absorbed into a

lower value of β (adding, e.g., an exciton binding energy of 0.5 eV to the experimentally determined energies

of T1 would require setting β ≈ 0.86).

S6

VI. SUPPORTING UV-VIS ABSORPTION DATA

A. Optical Absorption Spectroscopy on (1) Doped with (2a-c) and (3)

T1T2

Opt

ical

den

sity

/ ar

br. u

nits

Opt

ical

den

sity

/ ar

br. u

nits

Opt

ical

den

sity

/ ar

br. u

nits

Opt

ical

den

sity

/ ar

br. u

nits

Energy / eV Energy / eV

Energy / eV Energy / eV

(1) doped with (2a) (1) doped with (2b)

(1) doped with (2c) (1) doped with (3)

pure (1)

pure (1)

pure (1)

pure (1)

pure (2a)

pure (2c)pure (3)

50%

25%

17%

10%

(a)

(c)

(b)

(d)

T1T2 pure (2b) 50%

25%

17%

10%

T1T2

50%

25%

17%

10%

50%

25%17%

T1T2

4.0 3.5 3.0 2.5 2.0 1.5 1.0

010

17

50

25

100

4.0 3.5 3.0 2.5 2.0 1.5 1.0

0

10

17

50

25

100

4.0 3.5 3.0 2.5 2.0 1.5 1.0

010

17

50

25

100

4.0 3.5 3.0 2.5 2.0 1.5 1.0

010

17

50

25

100

FIG. S6. Optical absorption spectroscopy results on films of (1) doped with acceptors (a) (2a), (b) (2b),

(c) (2c), and (d) (3) at different dopant ratios; films prepared by spin coating in inert atmosphere from

CHCl3 solution on quartz samples. The spectra for (2d) are depicted in Fig. 3 of the main text.

S7

B. Schematic Energy Level Diagrams

- 4.5

Ene

rgy

w.r.

t. E

Vac / e

V

- 4.0

- 5.0

- 5.5

- 6.0

- 6.5

- 3.5

N

N

F F

F F

N

N

N

N

F

F

N

N

F

F

F F

N

N

N

N

N

N

F

F

N

N

EF

HCpx

HOsc

LCpx

LAcc

HCpx-1

N

N

FN

N

1.661.57 1.50

1.34 1.292.20

2.11 2.05

1.88 1.85

2a

2c2b

2d 3

1 1 1 1 1

FIG. S7. Schematic energy-level diagrams of the complexes formed by (1) with dopants (2a-d) of increasing

EA (from left to right). HOsc and LAcc denote the HOMO and LUMO levels of (1) and the dopant,

respectively. HCpx and H−1Cpx are the two highest occupied and LCpx the lowest unoccupied supramolecular

hybrid orbital of the (1)/(2a-d) complexes; EF denotes the Fermi energy, which is assumed at mid-gap of

the complex in the 1:1 cases. HOsc is calculated to 5.65 eV for (1) by DFT, the EA values for (2a-d) (LAcc)

stem from inverse photoelectron spectroscopy [4], and that for (3) from DFT calculations (see Fig. S4).

Note that for the difference between HHyb and LHyb the optical gap is indicated, which is lower than the

transport gap by the exciton binding energy.

S8

C. Optical Absorption Spectroscopy on the Ionized Dopants (2a-d)

4.0 3.5 3.0 2.5 2.0 1.5

0.0 eq

10.0 eq

Energy / eV

4.0 3.5 3.0 2.5 2.0 1.5

Energy / eV

0.0 eq

13.0 eq

4.0 3.5 3.0 2.5 2.0 1.5

0.0 eq

5.0 eq

Energy / eV

4.0 3.5 3.0 2.5 2.0 1.5Energy / eV

0.0 eq

10.0 eq

T2 T1

T2 T1

T2 T1T2 T1

Opt

ical

den

sity

/ ar

br. u

nits

Opt

ical

den

sity

/ ar

br. u

nits

Opt

ical

den

sity

/ ar

br. u

nits

Opt

ical

den

sity

/ ar

br. u

nits

Energy / eV Energy / eV

Energy / eV Energy / eV

Titration of (2a) with LiI Titration of (2b) with LiI

Titration of (2c) with LiI Titration of (2d) with LiI

(a)

(c)

(b)

(d)

1.472 eV

1.466 eV

1.449 eV1.469 eV

FIG. S8. (a-d) Evolution of absorption spectra of the dopants (2a-d) upon titration with increasing

equivalents (eq) of LiI in CH3CN solution yielding FxTCNQ radical anions according to the reaction

3LiI + 2FxTCNQ→ 2FxTCNQLi + LiI3 [6]. The transitions assigned to the ionized dopants arise at es-

sentially identical positions (most intense peaks at 2a: 1.472 eV, 2b: 1.466 eV, 2c: 1.469 eV, 2d: 1.449 eV)

[6–9]. They differ from those of the respective complexes with compound (1), indicated as T1 and T2,

in energy, in their shape (cf. main manuscript), and, importantly, in that they do not shift with dopant

strength (i.e., degree of fluorination).

S9

VII. SINGLE CRYSTAL SOLUTION OF THE (1)-(2A-D) MIXED CRYSTALS

A. Crystal data

Compounds (1)-(2a) (1)-(2b) (1)-(2c) (1)-(2d)

Formula Weight 725.06 743.05 761.04 797.03

Crystal Color, Habit black, needle-like black, needle-like black, needle-like black, needle-like

Crystal Dimensions 0.5x0.5x10 mm 0.5x0.5x10 mm 0.5x0.5x10 mm 0.5x0.5x10 mm

Crystal System triclinic triclinic triclinic triclinic

Lattice Type primitive primitive primitive primitive

a = 7.1901(3) A 7.1743(9) A 7.1609(5) A 7.0715(5) A

b = 7.7142(4) A 7.7822(10) A 7.8523(6) A 8.0773(6) A

c = 19.8510(14) A 19.852(3) A 19.8799(16) A 19.8477(14) A

α= 96.265(7)◦ 96.595(7)◦ 97.021(7)◦ 97.718(6)◦

β= 93.168(7)◦ 93.249(7)◦ 93.286(7)◦ 94.049(6)◦

γ= 106.512(8)◦ 106.783(8)◦ 107.556(8)◦ 107.845(5)◦

V = 1045.0(2) A3 1049.4(2) A3 1052.53(15) A3 1061.82(13) A3

Space Group P-1 P-1 P-1 P-1

Z value 1 1 1 1

calculated density 1.152 g cm−3 1.176 g cm−3 1.201 g cm−3 1.246 g cm−3

collected reflections 21449 21197 21635 21606

unique reflections 3784 3796 3809 3841

Rint 0.0587 0.0618 0.1082 0.0988

radiation Cu Kα Cu Kα Cu Kα Cu Kα

exposure time 15 sec/◦ 20 sec/◦ 30 sec/◦ 15 sec/◦

detector distance 191 mm 191 mm 191 mm 191 mm

2Θmax 136.5◦ 136.5◦ 136.5◦ 136.5◦

TABLE S2. Single crystal data for the 1:1 mixed crystal structures of (1) with (2a-d) grown from CHCl3

solution. A Rigaku R-AXIS RAPID 191R single-crystal diffractometer with filtered Cu-Kα radiation was

used recording 72 oscillation images, readout in 0.1 mm pixel mode. A linear absorption coefficient µ for Cu-

Kα radiation of 15.810 cm−1 was applied; empirical absorption correction resulted in transmission factors

0.486 - 0.854; data corrected for Lorentz and polarization effects.

S10

B. Structure refinement

The structures were solved by direct methods [10] and expanded using Fourier techniques.

The non-hydrogen atoms were refined anisotropically. Hydrogen atoms were refined using the

riding model. Data for (2a/2b/2c/2d): The final cycle of full-matrix least-squares refinement

(least squares function minimized:∑w(F 2

0 − F 2c )2) on F2 was based on 3784/3796/3809/3841

observed reflections and 235/253/254/253 variable parameters unweighted and weighted agree-

ment factors of: R1 =∑||F0| − |Fc||/

∑|F0| = 0.052/0.056/0.058/0.068, wR2 = [

∑(w(F 2

0 −

F 2c )2)/

∑w(F 2

0 )2]1/2 = 0.1437/0.1782/0.1583/0.1939; standard deviation of an observation of unit

weight was 1.01/1.05/0.95/0.95; maximum and minimum peaks on the final difference Fourier

map corresponded to 0.22/0.33/0.39/0.45 and -0.17/-0.23/-0.21/-0.34 e−/A3, respectively. Neu-

tral atom scattering factors were taken from Cromer and Waber [11]. Anomalous dispersion effects

were included in Fc [12]; the values for ∆f ′ and ∆f ′′ were those of Creagh and McAuley [13]; those

for the mass attenuation coefficients of Creagh and Hubbell [14]. All calculations were performed

using the CrystalStructure [15] crystallographic software package except for refinement, which was

performed using SHELXL-97 [16].

0.0 0.5 1.0 1.5 2.0qz / Å

-1

Log(

Inte

nsity

) / a

rbr.

units

2a

1

2b

2c

2d

FIG. S9. Comparison of the calculated powder diffraction patterns of the (1)-(2a-d) mixed crystal to that

of pure (1) [17]; intensities are normalized to the respective (001)-reflection.

S11

[1] H. Ebata, T. Izawa, E. Miyazaki, K. Takimiya, M. Ikeda, H. Kuwabara, T. Yui, J. Am. Chem. Soc.

2007, 129 (51), 15732.

[2] J. D. Chai, M. Head-Gordon, Phys. Chem. Chem. Phys. 2008, 10 (44), 6615–6620.

[3] C. Adamo, V. Barone, J. Chem. Phys. 1999, 110 (13), 6158–6170.

[4] K. Kanai, K. Akaike, K. Koyasu, K. Sakai, T. Nishi, Y. Kamizuru, T. Nishi, Y. Ouchi, K. Seki, Appl.

Phys. A 2009, 95 (1), 309–313.

[5] E. Huckel, Zeitschrift Fur Physik 1931, 70 (3-4), 204–286.

[6] L. R. Melby, R. J. Harder, W. R. Hertler, W. Mahler, R. E. Benson, W. E. Mochel, J. Am. Chem. Soc.

1962, 84 (17), 3374–3387.

[7] T. Shimizu, T. Yamamoto, Inorg. Chim. Acta 1999, 296 (1), 278–280.

[8] D. T. Duong, C. Wang, E. Antono, M. F. Toney, A. Salleo, Org. Electron. 2013, 14 (5), 1330–1336.

[9] I. Zanon, C. Pecile, J. Phys. Chem. 1983, 87 (19), 3657–3664.

[10] M. C. Burla, R. Caliandro, M. Camalli, B. Carrozzini, G. L. Cascarano, L. De Caro, C. Giacovazzo,

G. Polidori, R. Spagna, J. Appl. Crystallogr. 2005, 38, 381–388.

[11] J. T. Cromer, D. T. Waber, International Tables for X-ray Crystallography, The Kynoch Press, Birm-

ingham (England), 1974.

[12] W. C. Ibers, J. A. Hamilton, Acta Cryst. 1964, 17, 781.

[13] W. Creagh, D. C. McAuley, International Tables for Crystallography, Bd. C, (Hrsg.: A. Wilson), Kluwer

Academic Publishers (Boston), 1992, 219–222, Table 4.2.6.8.

[14] J. Creagh, D. C. Hubbell, International Tables for Crystallography, Bd. C, (Hrsg.: A. Wilson), Kluwer

Academic Publishers (Boston), 1992, 200–206, Table 4.2.4.3.

[15] Crystal Structure Analysis Package, Rigaku Corporation (2000-2013), Tokyo 196-8666, Japan.

[16] G. M. Sheldrick, Acta Cryst. A 2008, 64, 112–122.

[17] T. Izawa, E. Miyazaki, K. Takimiya, Adv. Mater. 2008, 20 (18), 3388.

S12