Nature - USA (2020-10-15)

388 | Nature | Vol 586 | 15 October 2020

Article

400450500550600

0 h

9 h

20 h

33 h

50 h

69 h

0246

Current density (mA cm

–2)

102

100

0

1

2

3

4

5

0 100 200 300 400 500

Voltage (V)

02468

V (V)

J (mA cm

–2)

400 450 500 550 600 650 700

a b

c d

Intensity

C/S/S

3.1 V

C/S/S-Cl(f)

2.8 V

h+

e–

Wavelength (nm)

Intensity

EL PL

*

C/S/S

C/S/S-Cl(f)

C/S/S-Cl(l)

Cl(f)/Cl(l)

C/S/S

C/S/S-Cl(f)

C/S/S-Cl(l)

No QDs

C/S/S-Cl(l)

2.9 V

10 –2

10 –4

Initial

T 50

T 50

10 –3

10 –1

101

103

C/S/S

C/S/S-Cl(f)

C/S/S-Cl(l)

No QDs

EOD HOD

3.0 2.5 2.0

3.0 2.5 2.0

Energy (eV)

Voltage (V)

Wavelength (nm) Wavelength (nm) Time (h)

400450500550600650

0 h

9 h

20 h

33 h

50 h

69 h

3.0 2.5 2.0

Energy (eV)

Fig. 4 | Analysis of device characteristics. a, Current density (J)–voltage (V)
characteristics of EODs and HODs with no QDs, C/S/S, C/S/S-Cl(l) and C/S/S-Cl(f )
QDs. b, Electroluminescence (EL) spectra of QD-LEDs with the top EML
containing red-emitting QDs and various bottom EMLs: C/S/S, C/S/S-Cl(l) and
C/S/S-Cl(f ). c, Time-dependent electroluminescence and photoluminescence

spectra measured from a QD-LED with double EML at an initial brightness of

2,000 cd m−2. The asterisk marks the emission from the HTL. d, Voltage change

during the operation of the QD-LEDs. Inset, J–V profiles of the QD-LED with

double EML before (initial) and after (T 50 ) operation.

–4.9

–5.4 –5.6

–2.8 –2.7

–3.2

–2.9

–3.4

–4.3

PEDOTTFB

Cl(

l)

ITO Al

ZnMgO

C/S/SCl(f)

–5.5

–2.7

350 450 550 650

Intensity

3.5 3.0 2.5 2.0

Energy (eV)

Al

ITO

PEDOT (35 nm)

TFB (25 nm)

ZnMgO (20 nm)

Cl(f) (28 nm)

Cl (%)

Cl(l) (12 nm)

0

5

10

15

20

02468

EQE (%)

02468

Luminance (×10

4 cd m

–2

)

0

20

40

60

80

100

0 100 200 300 400 500

8.0V

7.0V

6.0V

5.0V

4.0V

3.4V

abc

d e f

0

C/S/S

C/S/S-Cl(l)

C/S/S-Cl(f)

Cl(f)/Cl(l)

C/S/S

C/S/S-Cl(l)

C/S/S-Cl(f)

Cl(f)/Cl(l)

C/S/S

C/S/S-Cl(l)

C/S/S-Cl(f)

Cl(f)/Cl(l)

–6.0

–5.7

–8 –7.8

–7

–6

–5

–4

–3

–2

Voltage (V) Luminance (×10^4 cd m–2) Time (h)

Wavelength (nm)

Current density (mA cm

–2)

Energy (eV)

8

6

4

2

10

10 –1

101

103

10 –3

Luminance (%)

0.0

0.2

0.1

0.8

1.2

1.4

0.0

Fig. 3 | Performance of QD-LEDs. a, Energy-band diagram of the QD-LEDs. The
grey square indicates the energy level of the C/S/S-OA QD before chlorination.
b, Cross-sectional TEM image (scale bar, 30 nm) of the QD-LED with double
EML. The vertical concentration of Cl was measured using high-resolution TEM
EDX (Extended Data Fig. 5e, f ). c, Voltage-dependent electroluminescence

spectra of the QD-LED with double EML. Inset, photographs of the operating

devices. d, Voltage-dependent current density (left axis) and luminance (right

axis). e, Luminance dependence of the EQE. f, Operation lifetime of the

QD-LEDs measured at the initial brightness of 650 cd m−2.