1

Electronic Supplementary Information (ESI)

New insight on intramolecular conjugation in the design of efficient blue

materials: from the control of emission to absorption

Jie Yang†,#, Qingxun Guo‡,#, Zichun Ren†, Xuming Gao†, Qian Peng§, Qianqian Li†, Dongge Ma‡,*,

and Zhen Li†,*

†Department of Chemistry, Hubei Key Lab on Organic and Polymeric Opto-Electronic Materials,

Wuhan University, Wuhan 430072, China. Fax: (86)27-68756757. E-mail: lizhen@whu.edu.cn;

lichemlab@163.com. ‡Changchun Institute of Applied Chemistry, The Chinese Academy of Sciences Changchun

130022, China. E-mail: mdg1014@ciac.jl.cn. §Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Science (BNLMS),

Institute of Chemistry, Chinese Academy of Sciences, 100190 Beijing, China. # These authors contributed equally to this work.

Table of Contents Experimental Section

Figure S1 The effect of chromophore effect and auxochrome effect on adjusting the maximum

absorption wavelength (λabs).

Scheme S1 The synthetic routes to Cz-3tPE, TPA-3TPP and Cz-3TPP.

Figure S2 TGA curves (A) and DSC curves (B, C, D) for Cz-3tPE, TPA-3TPP and Cz-3TPP recorded

under N2 at a heating rate of 15 °C/min. Figure S3 UV-vis spectra of CzPh, TPA and tPE in THF solution (concentration ≈ 10 µM).

Figure S4 The chemical structures and the corresponding maximum absorption wavelengths

(λabs) for CzPh, TPA, TPP and tPE.

Figure S5 (A) UV-vis spectra of Cz-3tPE in different solutions, concentration ≈ 10 µM; (B) UV-vis

spectra of TPA-3TPP in different solutions, concentration ≈ 10 µM; (C) The UV spectra of

Cz-3TPP in different solutions, concentration ≈ 10 µM.

Figure S6 PL spectra in different solutions and the corresponding quantum yields for Cz-3tPE,

concentration ≈ 10 µM.

Figure S7 Linear correlation of orientation polarization (f) of solvent media with the Stokes shift

for Cz-3tPE (A), TPA-3TPP (B) and Cz-3TPP (C).

Table S1 Detailed absorption and emission peak positions of Cz-3tPE, TPA-3TPP and Cz-3TPP in

different solvents and the calculated ground-state dipole moment (μg), excited state dipole

moment (μe).

Figure S8 PL spectra of films and EL spectra for Cz-3tPE (A), TPA-3TPP (B) and Cz-3TPP (C), respectively.

Figure S9 The chemical structures, maximum absorption wavelengths (λabs), EL emission peaks

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C.This journal is © The Royal Society of Chemistry 2017

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(λEL), external quantum yields (EQE) of TPA-3TPP, TTPECaP, Cz-3tPE, Cz-3TPP and the responding

different λabs and λEL effects.

Figure S10 The PL spectra in THF/n-hexane mixtures with different n-hexane fractions: (A) Cz-3tPE, concentration ≈ 10 µM; excitation wavelength 330 nm; (B) TPA-3TPP, concentration ≈

10 µM; excitation wavelength 340 nm; (C) Cz-3TPP, concentration ≈ 10 µM; excitation

wavelength 310 nm.

Figure S11 Calculated molecular orbital amplitude plots of HOMO and LUMO levels and

optimized molecular structures of Cz-3tPE, TPA-3TPP and Cz-3TPP.

Figure S12 The cyclic voltammograms of Cz-3tPE, TPA-3TPP and Cz-3TPP recorded in

dichloromethane.

Figure S13 The changes in power efficiency with the current density.

Figure S14 MALDI-TOF of Cz-3tPE.

Figure S15 MALDI-TOF of TPA-3TPP.

Figure S16 MALDI-TOF of Cz-3TPP.

Experimental Section

Characterizations 1H and 13C NMR spectra were conducted on a Mecuryvx300 or Ascend 400 MHz

spectrometer. Elemental analyses of carbon, hydrogen and nitrogen were taken on a

Carlo-Erba-1106 microanalyzer. Mass spectra were measured on a Voyager DESTR MALDI-TOF

mass spectrometer. UV-Vis absorption spectra were measured on a Shimadzu UV-2500

recording spectrophotometer. Photoluminescence spectra were recorded on a Hitachi F-4600

fluorescence spectrophotometer. Differential scanning calorimetry (DSC) was performed on a

NETZSCHDSC 200 PC instrument from room temperature to 300 oC at a heating rate of 15 oC

min-1 under argon. Thermogravimetric analysis (TGA) was measured on a NETZSCH STA 449C

instrument. The thermal stabilities of the samples under a nitrogen atmosphere were

determined by measuring their weight loss while heating from room temperature to 700 oC at a

rate of 15 oC min-1. Cyclic voltammetry (CV) was carried out on a CHI voltammetric analyzer in

three electrode cells with a platinum counter electrode, an Ag/AgCl reference electrode, and a

glassy carbon working electrode at a scan rate of 100 mV s-1 in anhydrous dichloromethane

solution with 0.1 M tetrabutylammonium perchlorate as the supporting electrolyte and purged

with nitrogen. The potentials obtained in reference to the Ag/Ag+ electrode were converted

into values versus the saturated calomel electrode (SCE) by means of ferrocenium/ferrocene

(Fc+/Fc) standard. Fluorescence quantum yields of powders and THF solutions were determined

with a HamamatsuC11347 Quantaurus-QY absolute fluorescence quantum yield spectrometer.

Solvatochromic effect The influence of solvent environment on the optical property of our compounds can be

understood using the Lippert-Mataga equation:

𝑣𝑎 − 𝑣𝑓 =1

4𝜋𝜀0∗2𝛥𝜇2

ℎ𝑐𝑎3𝛥𝑓 + 𝐶𝑜𝑛𝑠𝑡.

where a = √3𝑀

4𝜋𝑑𝑁𝑎

3

3

In the above equations, va-vf is the Stokes shift, ε0 is the vacuum permittivity, h is Planck’s

constant, c is the velocity of light, a is the Onsager radius of fluorophore, Δμ = μe - μg is the

difference in the dipole moment of fluorophore between the excited (μe) and the ground (μg)

states, e and n are the static dielectronic constant and the refractive index of the solvent,

respectively, Δf is the orientation polarizability, M is the molecular weight, d is the density of

molecule, and Na is Avogadro’s number. Therefore, based on equation, the change in dipole

moment, Δμ = μe - μg, can simply be estimated from the slope of a plot of va-vf against Δf.

Computational details

The molecular structures, orbital distributions of HOMO and LUMO energy levels and the

ground state dipole moments (μg) were optimized at B3LYP/6-31g* level using Gaussian 09

program.

The hole-only devices and measurement

The hole-only devices were fabricated on glass substrates. Prior to deposition, the substrate

was thoroughly cleaned in an ultrasonic bath using subsequently detergents and deionized

water. The structures of devices were ITO/MoO3/Cz-3tPE or TPA-3TPP or Cz-3TPP (110

nm)/MoO3/Al, and layers, Cz-3tPE, TPA-3TPP and Cz-3TPP, were grown in succession by thermal

evaporation without breaking vacuum (10-5 Pa). Here, the interfacial layer MoO3 worked as

hole-injection and electron-blocking layers. The Al electrodes were deposited on the substrates

through shadow masks. The current-voltage (I–V) characteristics were carried out using a

Keithley 2400 sourcemeter integrated with a vacuum cryostat (Optistat DN-V, Oxford

Instruments). The admittance was measured at room temperature by using an Agilent E4980A

precision LCR meter in the frequency range of 20 Hz–13 MHz with the oscillation amplitude of

the ac voltage kept at 100 mV.

OLED devices and measurement

The hole-transporting material of NPB (1,4-bis(1-naphthylphenylamino)-biphenyl), electron

blocking material of 1,3-Di-9-carbazolylbenzene (MCP) and electron transporting materials of

1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi) and

1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB) were obtained from a commercial source. The

EL devices were fabricated by vacuum deposition of the materials at a base pressure of 10−5

Torr onto glass pre-coated with a layer of indium tin oxide (ITO) with a sheet resistance of 25 Ω

per square. Before deposition of an organic layer, the clear ITO substrates were treated with

oxygen plasma for 2 min. The deposition rate of organic compounds was 1–2 Å s −1. Finally, a

cathode composed of lithium fluoride (1 nm) and aluminium (100 nm) was sequentially

deposited onto the substrate in the vacuum of 10−5 Torr. The L–V–J of the devices was

measured with a Keithey 2400 Source meter and a Keithey 2000 Source multimeter equipped

with a calibrated silicon photodiode. The EL spectra were measured by JY SPEX CCD3000

spectrometer. All measurements were carried out at room temperature under ambient

conditions.

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Figure S1 A new sight on the intramolecular conjugation in the design of efficient blue

materials―from the control of emission to absorption: the chromophore effect (the maximum

absorption wavelengths increase with the addition of double bond, nearly 30 nm per double

bond) and auxochrome effect (the maximum absorption wavelengths increase with the

enhanced electron donating ability for auxochrome) on adjusting the maximum absorption

wavelength (λabs).

Scheme S1 The synthetic routes to Cz-3tPE, TPA-3TPP and Cz-3TPP.

5

50 100 150 200 250 300

-20

-10

0

10

20

<exo H

ea

t F

low

en

do>

Temperature (oC)

Cz-3tPE

Tg=186

oCT

c=198

oC

(B)

Figure S2 TGA curves (A) and DSC curves (B, C, D) for Cz-3tPE, TPA-3TPP and Cz-3TPP recorded

under N2 at a heating rate of 15 °C/min.

250 300 350 400 450

0.0

0.1

0.2

0.3

Ab

so

rban

ce (

au

)

Wavelength (nm)

CzPh

TPA

tPE

Figure S3 UV-vis spectra of CzPh, TPA and tPE in THF solution (concentration ≈ 10 µM).

100 200 300 400 500 600 700

20

40

60

80

100

Weig

ht

(%)

Temperature (oC)

Cz-3tPE

TPA-3TPP

Cz-3TPP

(A)

75 125 175 225 275

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

8

10

<exo H

eat

Flo

w e

nd

o>

Temperature (oC)

TPA-3TPP

(C)

50 100 150 200 250 300

-40

-20

0

20

40

<exo H

eat

Flo

w e

ndo>

Temperature (oC)

Cz-3TPP

Tg=194

oC

(D)

6

Figure S4 The chemical structures and the corresponding maximum absorption wavelengths

(λabs) for CzPh, TPA, TPP and tPE.1

280 330 380 430 480

0.0

0.2

0.4

0.6

0.8

Ab

so

rban

ce (

au

)

Wavelength (nm)

Toluene

THF

DCM

DMF

(A)

280 330 380 430 480

0.0

0.3

0.6

0.9

Ab

so

rban

ce (

au

)

Wavelength (nm)

Toluene

THF

DCM

DMF

(B)

280 330 380 430

0.0

0.2

0.4

0.6

0.8

Ab

so

rba

nc

e (

au

)

Wavelength (nm)

Toluene

THF

DCM

DMF

(C)

Figure S5 (A) UV-vis spectra of Cz-3tPE in different solutions, concentration ≈ 10 µM; (B) UV-vis

spectra of TPA-3TPP in different solutions, concentration ≈ 10 µM; (C) UV-vis spectra of Cz-3TPP

in different solutions, concentration ≈ 10 µM.

Figure S6 PL spectra in different solutions and the corresponding quantum yields for Cz-3tPE,

concentration ≈ 10 µM.

7

0.0 0.1 0.2 0.3

5900

6100

6300

6500

6700

va-v

f (c

m-1)

f

(A)

0.0 0.1 0.2 0.3

3400

3800

4200

4600

5000

5400

5800

va-v

f (c

m-1)

f

(B)

0.0 0.1 0.2 0.3

5500

6000

6500

7000

7500

8000

8500

va-v

f (c

m-1)

f

Figure S7 Linear correlation of orientation polarization (f) of solvent media with the Stokes shift

(υa−υf; a: absorbed light; f: fluorescence) for Cz-3tPE (A), TPA-3TPP (B) and Cz-3TPP (C).

Table S1 Detailed absorption and emission peak positions of Cz-3tPE, TPA-3TPP and Cz-3TPP in

different solvents and the calculated ground-state dipole moment (μg), excited state dipole

moment (μe).

Compounds Solvents f λa (nm) λf (nm) va-vf (cm-1) μga (D) μe

b (D)

Cz-3tPE

PhMe 0.014 351 445 6018

3.3 12.9 THF 0.210 351 450 6268

DCM 0.217 348 451 6563

DMF 0.276 352 460 6670

TPA-3TPP

PhMe 0.014 363 417 3567

0.1 18.8 THF 0.210 362 435 4636

DCM 0.217 363 445 5076

DMF 0.276 364 460 5733

Cz-3TPP

PhMe 0.014 312 383 5942

2.9 22.3 THF 0.210 313 398 6823

DCM 0.217 311 405 7643

DMF 0.276 312 423 8411

400 450 500 550 600

No

rmalize

d P

L/E

L In

ten

sit

y (

au

)

Wavelength (nm)

Film

EL (A)

EL (B)

(A)

400 450 500 550 600

No

rma

lize

d P

L/E

L I

nte

ns

ity

(a

u)

Wavelength (nm)

Film

EL(C)

EL(D)

(B)

350 400 450 500 550

No

rmalize

d P

L/E

L In

ten

sit

y (

au

)

Wavelength (nm)

Film

EL (E)

EL (F)

(C)

Figure S8 PL spectra of films and EL spectra for Cz-3tPE (A), TPA-3TPP (B) and Cz-3TPP (C), respectively. Device configurations for EL (A) and EL (C): ITO/MoO3/NPB (50 nm)/MCP (10

8

nm)/Cz-3tPE or TPA-3TPP (15 nm )/TPBi (35 nm)/LiF/Al; Device configurations for EL (B), EL (D)

and EL (E): ITO/MoO3/Cz-3tPE or TPA-3TPP or Cz-3TPP (75 nm)/TPBi (35 nm )/LiF/Al; Device

configuration for EL (F): ITO/MoO3/Cz-3TPP (75 nm)/TmPyPB (35 nm )/LiF/Al.

Figure S9 The chemical structures, maximum absorption wavelengths (λabs), EL emission peaks

(λEL), external quantum efficiencies (EQE) of TPA-3TPP, TTPECaP, Cz-3tPE, Cz-3TPP and the

corresponding different λabs and λEL effects (Note: Cz-3tPE, Cz-3TPP and TPA-3TPP were

reported in this paper, and TPA3HTPE was reported in reference 2 ).

350 400 450 500 550 600

0

500

1000

1500

2000

2500

PL

In

ten

sit

y (

au

)

Wavelength (nm)

0

20

40

60

80

99

fn (vol%)

(A)

350 400 450 500 550 600

0

2000

4000

6000

8000

10000

PL

In

ten

sit

y (

au

)

Wavelength (nm)

0

20

40

60

80

99

fn (vol%)

(B)

350 400 450 500 550

0

3000

6000

9000

PL

In

ten

sit

y (

au

)

Wavelength (nm)

0

20

40

60

80

99

fn (vol%)

(C)

Figure S10 PL spectra in THF/n-hexane mixtures with different n-hexane fractions: (A) Cz-3tPE,

concentration ≈ 10 µM; excitation wavelength 330 nm; (B) TPA-3TPP, concentration ≈ 10 µM;

excitation wavelength 340 nm; (C) Cz-3TPP, concentration ≈ 10 µM; excitation wavelength 310

nm.

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Figure S11 Calculated molecular orbital amplitude plots of HOMO and LUMO levels and

optimized molecular structures of Cz-3tPE, TPA-3TPP and Cz-3TPP.

-0.4 0.1 0.6 1.1 1.6

0.00000

-0.00001

-0.00002

Cu

rre

nt

(A)

Potential vs SCE (V)

Cz-3TPP

Cz-3tPE

TPA-3TPP

Figure S12 The cyclic voltammograms of Cz-3tPE, TPA-3TPP and Cz-3TPP recorded in

dichloromethane.

0.1 1 10 100 1000

0.01

0.1

1

10

Po

wer

Eff

icie

ncy (

lm/W

)

Current Density (mA/cm2)

device A device B

device C device D

device E device F

Figure S13 The changes in power efficiency with the current density. Device configurations for

A and C: ITO/MoO3/NPB (50 nm)/MCP (10 nm)/Cz-3tPE or TPA-3TPP (15 nm )/TPBi (35

nm)/LiF/Al; Device configurations for B, D and E: ITO/MoO3/Cz-3tPE or TPA-3TPP or Cz-3TPP (75

nm)/TPBi (35 nm )/LiF/Al; Device configuration for F: ITO/MoO3/Cz-3TPP (75 nm)/TmPyPB (35

nm )/LiF/Al.

10

800 900 1000 1100 1200 1300 1400

0

1000

2000

3000

4000

5000

6000

Inte

ns

ity

M/Z

Cz-3tPE

1005.0559

Figure S14 MALDI-TOF of Cz-3tPE.

800 900 1000 1100 1200 1300 1400

0

2000

4000

6000

8000

10000

12000

14000

Inte

ns

ity

M/Z

TPA-3TPP1157.1414

Figure S15 MALDI-TOF of TPA-3TPP.

11

800 900 1000 1100 1200 1300 1400

0

10000

20000

30000

40000

50000

60000

Inte

nsit

y

M/Z

Cz-3TPP 1155.2246

Figure S16 MALDI-TOF of Cz-3TPP.

Reference

1 V. Vergadou, G. Pistolis, A. Michaelides, G. Varvounis, M. Siskos, N. Boukos and S. Skoulika,

Cryst. Growth Des., 2006, 6, 2486.

2 G. Chen, W. Li, T. Zhou, Q. Peng, D. Zhai, H. Li, W. Yuan, Y. Zhang and B. Z. Tang, Adv. Mater., 2015, 27, 4496.