Synthesis, Characterization and Applications of All-Inorganic Perovskite Light-emitting

Semiconducting Quantum DotsShin-Ying Lin(林欣穎) and Ru-Shi Liu*(劉如熹)

Department of Chemistry, National Taiwan University, Taipei 106, TaiwanAbstract

The cubic structure of zero-dimension all-inorganic perovskite quantum dots (CsPbX3, X=Cl, Br, I) nanomaterials which were synthesized by colloidal solutionmethod as luminescent materials for light emitting diode(LED) backlight display applications. In this study, we tuned halogen composition ratio and investigatedparticle size and band gap difference to explain the spectral shift. We controlled the Br/I ratio of CsPb(Br1-xIx)3 and analyzed their different optical properties to expectto find a correlation of the spectral shift and therefrom establish a general explain. We also focused on this all-inorganic perovskite-type quantum dot which wasapplied for the first time for white light emitting diodes. With varying proportions of blue, green and red QD’s, a narrow, white light-emitting material was produced.Further, mesoporous silica particle loaded with perovskite-type quantum dots was also investigated to resolve problems of ion-exchange during LED packaging andthese novel nanocomposite perovskite-type quantum dots were successfully applied for LED devices.

This work was supported by the Ministry of Science and Technology of Taiwan (Contract

No. 104-2923-M-002-007-MY3) and Lextar Electronics Corporation, Taiwan.

Tuning halogen ratio of CsPb(Br1-xIx)3 Application of P-QDs in white LEDs

20 30 40 50

20 30 40 50

2 Theta (degree)

CsPbI3 - ICSD:181288

x = 1

Inte

nsi

ty (

a.u

.)

x = 0.8

x = 0.6

x = 0.4

x = 0.2

x = 0

CsPbBr3 - ICSD:29073

5 10 15 20 25 30

observed

calculated

difference

bragg

Inte

nsi

ty (

a.u

.)

2 Theta (degree)

5 10 15 20 25 30

Inte

nsi

ty (

a.u

.)

2 Theta (degree)

observed

calculated

difference

bragg

CsPbBr3

CsPbI3

X-ray diffraction Pawley refinement

Summary

TEM

Photoluminescence

500 550 600 650 700 750

No

rma

lize

d I

nte

nsi

ty (

a.u

.)

Wavelength (nm)

x = 0

x = 0.2

x = 0.4

x = 0.6

x = 0.8

x = 1

CsPb(Br1-x/Ix)3

0.0 0.2 0.4 0.6 0.8 1.014000

15000

16000

17000

18000

19000

20000CsPb(Br1-xIx)3

Wa

ven

um

ber

(cm

-1)

x

Absorbance - Band Gap

500 550 600 650 700 750x = 0.0

x = 0.2

x = 0.4

x = 0.6

x = 0.8

CsPb(Br1-x/Ix)3

Wavelength (nm)

x = 1.0

3.0 2.5 2.0 1.5

CsPb(Br1-xIx)3

(A h

v)2

(eV

cm

-1)2

Energy (eV)

x = 1

x = 0.8

x = 0.6

x = 0.4

x = 0.2

x = 0

3.0 2.5 2.0 1.5

CsPb(Br1-xIx)3 Band Gap (eV)

Difference

x = 0 2.41

x = 0.2 2.36

x = 0.4 2.23

x = 0.6 1.97

x = 0.8 1.83

x = 1 1.79

0.05

0.13

0.25

0.14

0.05

cubic

cubic

531nm

566 nm

LED strategy

400 500 600 700 800

Norm

ali

zed

In

ten

sity

(a.u

.)

Wavelength (nm)

400 500 600 700 800

Wavelength (nm)

Norm

ali

zed

In

ten

sity

(a.u

.)

CsPb(Br0.4I0.6)3 CsPbBr3

625 nm FWHM : 30 nm

515 nm FWHM : 20 nm

400 500 600 7000.0

0.2

0.4

0.6

0.8

1.0

Wavelength (nm)

Norm

ali

zed

In

ten

sity

(a.u

.)

G-PQDs

R-PQDs

G-PQDs + R-PQDs

30 40 50 60 70 80 90 100

0

20

40

60

80

100

Temperature (oC)

Rel

ati

ve

Inte

nsi

ty (

%)

CsPbBr3

MP-CsPbBr3

1 2 4 8 24 36 48 60 72 80 960.0

0.2

0.4

0.6

0.8

1.0

Time (hr)

Rel

ati

vel

y I

nte

nsi

ty (%

)

MP-CsPbBr3

CsPbBr3

Thermal stability

Light stability - 365 nm ex

400 500 600 700

EL

In

ten

sity

(a

.u.)

Wavelength (nm)

MP CsPbBr3 + CsPb(Br0.4I0.6)3

Color point (x/y)

0.30/0.28

For Backlighting

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

y

x

Rec.2020

LED

Panel

Rec .

Coverage 2020

(%)

84.9

NTSC (%)

113.6

400 500 600 700

EL

In

ten

sity

(a

.u.)

Wavelength (nm)

CsPbBr3 + K2SiF6 Color point (x/y)

0.28/0.25

For Backlighting

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

y

x

Rec.2020

LED

Panel

Rec .

Coverage 2020

(%)

83.3

NTSC (%)

119.7

400 500 600 700

EL

In

ten

sity

(au

)

Wavelength (nm)

NYAG4 + R-QD

光學理論

色點

0.43/0.38

實測值

lm CCT(K) Ra R9

30.9 2908 87.9 96.1

Publications and patents

H. C. Wang, S. Y. Lin, A. C. Tang, B. P. Singh, H. C. Tong, C. Y. Chen, Y. C. Lee, T. L

Tsai, and R. S. Liu*, “Mesoporous Silica Particle Integrated with All-Inorganic CsPbBr3

Perovskite Quantum Dot Nanocomposite (MP-PQDs) with High Stability and Wide Color

Gamut Used for Backlight Display”.( Angewandte Chemie in press) IF = 11.261

J. L. Leaño, Jr.,† S. Y. Lin†, S. Mahlikd, M. Grinbergd, Y. T. Tsai, C. C. Lin, V. V. Atuchin,

H. S. Sheu and R. S. Liu*, “Green light-excitable Ce-doped nitridomagnesoaluminate

Sr[Mg2Al2N4] phosphor for white light-emitting diodes”. (to be submitted on Chem.

Commun.)

B. P. Singh‡, S. Y. Lin‡, H. C. Wang, A. C. Tang and R. S. Liu*, “Improvement in color

rendering index of light emitting diode with inorganic red perovskite quantum dots

integrated on blue chip”.(to be submitted on Chem. Commun.)

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Ion exchange - mesoporous silica-PQDs

PQDs for white light emitting diode

XPS/XANES

13000 13050 13100 13150

Norm

ali

zed

In

ten

sity

( a

.u.)

Energy (eV)

PbO

PbO2

CsPbBr3

CsPb(Br0.8

/I0.2

)3

CsPb(Br0.6

/I0.4

)3

CsPb(Br0.4

/I0.6

)3

CsPbI3

Cs+ Pb2+

Br-I-

Pb4+

Pb2+

0.0 0.2 0.4 0.6 0.8 1.0

200

210

220

230

240

250

5.8

5.9

6.0

6.1

6.2

6.3

Vo

lum

e (

Å3)

x

CsPb(Br1-xIx)3

a (

Å)

14000 16000 18000 20000

CsPb(Br1-xIx)3

No

rma

lize

d I

nte

nsi

ty (

a.u

.)

Wavenumber (cm-1)

x = 0

x = 0.2

x = 0.4

x = 0.6

x = 0.8

x = 1

CsPb(Br0.2/I0.8)3 CsPbI3CsPb(Br0.4/I0.6)3

CsPbBr3 CsPb(Br0.6/I0.4)3CsPb(Br0.8/I0.2)3

(100)(100)

(100)

(100) (100)(100)