This ppt includes Copper halide ( CuI, CuBr and CuCl ) based tunable monochromatic and white LED.

1. Manish Kumar Sharma
107031857
Material Sciences and Engineering
Introduction to
Soft Condensed Matter

2. •Introduction
• Motivation
• Experimental work
• Results and Discussion
• Conclusion
Outline
b) PL emission spectra
a) UV-vis absorption spectra
Cu–Cl, Cu–Br and Cu–I NSASs under 365 nm excitation

3. Introduction LED vs. Regular lightbulbs
Light-Emitting Diodes (LEDs) have been part of daily life for
many decades, starting with indicator lamps and infrared remote
controls in the 1960s.
Yet it is only in 2014 that the Nobel Prize in Physics was
awarded for LEDs, and namely for blue LEDs that eventually
allowed one to produce white light.
Advantages of LED’s
 Long life
 Energy efficiency
 High brightness and intensity
 Exceptional color range
 Low radiated heat
 Reliability
 Instantaneous illumination
 Directional lighting
Cost vs Lifetime graph
Challenges of LED’s
Cost
Colour
Performance
Life expectancy of components
Colour shift
Interface with controls

4. Fluorescent Cu nanoclusters (NCs) have exhibited great
potential in the field of illumination and display, due to :
1. Low toxicity
2. Large reserves
3. Electrical properties
4. Optical properties
Motivation
 To adjust the emission color of Cu NC self-assemblies,
1. Doping metal
2. Capping ligands have been put forward recently.
It is still challenging to achieve full-color emission of Cu NC
self-assemblies because it is either dis-successive or successive
in a narrow range.
 Halogens (F, Cl, Br, I) are found widely existing in fluorescent materials and closely related to their emission properties
because incorporating halogens could directly tune the band gaps.
 In this work, the halogen (Cl, Br, I) effects are utilized to tune the emission of the Cu nanocluster self-assembly
nanosheets (NSASs).

5. Experimental Work
Synthesis of Cu NSASs
19.8 mg (0.20 mmol) of CuCl, 28.7 mg (0.20 mmol)
of CuBr and 38.1 mg (0.20 mmol) of CuI were
employed as the Cu source, respectively.
The Cu source was dissolved in 3 mL of BE and
sonicated in the open air for 30 s.
Then, 1 mL (4 mmol) of DT was added and stirred
at 60 °C for 20 min.
Synthesis of Cu NCASs
The synthesis procedure of Cu NCASs was similar to that
of the Cu NSASs, despite that mixed Cu sources were
employed.
9.9 mg (0.10 mmol) of CuCl and 14.4 mg (0.10 mmol) of
CuBr were dissolved in 3 mL of BE and sonicated for 30 s.
Then, 1 mL (4 mmol) of DT was added and stirred at 60 °C
for 20 min.
Purification
 First, 1 mL of chloroform and 2 mL of ethanol were added to 1 mL of the pristine products, followed by 7000 rpm
centrifugation for 5 min.
 The precipitates were re-dispersed in 1 mL of chloroform.
 The purification process was repeated twice to ensure the removal of the byproducts and residual ligands.
 The final products were dried under vacuum or re-dissolved in chloroform for further test and application.

6. XRD pattern
Only one main diffraction peak appears at 2.6° and the second and third
ordered peaks locate around 5.3 and 7.8°, which show that there is no
difference in layer or cluster spacing between the three Cu NSASs.
Results and Discussion
Plot of (αhv)2 versus photon energy
Band gap
Cu-Cl = 2.86eV
Cu-Br = 2.81eV
Cu-I = 2.73eV

7. Low magnification TEM images of Cu–Cl, Cu–Br and Cu–I NSASs
High magnification TEM images of Cu–Cl, Cu–Br and Cu–I NSASs
Insets of (d–f) are the corresponding size
distributions of Cu NCs
Continued…
HRTEM
Intensity
(a.u)
EDS analysis of Cu–Cl (blue), Cu–Br
(orange) and Cu–I (red) NSAS

8. (a) XPS Cu 2p spectra of the three Cu NSASs
(b) Cl 2p (c) Br 3d
(d) I 3d
XPS spectra of Cu-Cl, Cu-Br and Cu-I NSASs
Continued…
XPS

9. Schematic diagram of the triplet-state emission processes in (a) Cu–Cl NSASs, (b) Cu–Br NSASs and (c) Cu–I NSASs
S0, T1, and S1 represent the
ground state, excited triplet
state, and singlet state,
respectively.
Calculated structure, molecular
orbital isosurface and wave
function of electron motion of the
Cu NCs.
Color labels:
 Pink, Cu;
 Silver, C;
 White, H;
 Yellow, S;
 Green, Cl;
 Cyan, Br;
 Magenta I;
 Red, wave function positive phase;
 Blue, wave function negative phase
Continued…

10. PL emission (b, d, f, h) spectra of the Cu NCASs
obtained with mixed cuprous halides as the Cu source.
UV-vis absorption spectra (a, c, e, g) spectra of the Cu
NCASs obtained with mixed cuprous halides as the Cu source
Insets of (b),
(d), (f) and (h)
are the
corresponding
PL emission
image under
365 nm
excitation
Continued…
(a) UV-vis absorption
(b) PL emission spectra
 Cu–Cl
 Cu–Br
 Cu–I NSASs
Inset of (b) is
the fluorescent
images of the
Cu–Cl, Cu–Br
and Cu–I
NSASs under
365 nm
excitation.

11. Continued…
Cu NCASs obtained with equimolar amount
of CuCl, CuBr and CuI as the copper source.
(b) EDS analysis of the
composition of the obtained Cu
NCASs
(a) TEM images of the Cu NCASs
obtained with equimolar amount of
CuCl, CuBr and CuI as the Cu
sources.
Fabrication of White LED’s NCASs
The GaN LED chips with an emission peak at 365 nm and an operating voltage at 4.5 V
were purchased from Advanced Optoelectronic Technology CO., Ltd.
The PL emission spectra of the Cu NCASs
obtained at different storage time

12. Conclusion
They demonstrate that the emission color of Cu NSASs could be adjusted from cyan to yellow
and red by simply choosing CuCl, CuBr and CuI as the single starting Cu source, respectively.
DFT simulation reveals that the introduced halogens contribute to the HOMO of the Cu NCs,
and the SOC is enhanced due to the heavy atom effect from Cl to Br and I.
Monochromatic LED and WLED prototypes employing the Cu NSASs and NCASs as color
converters are further fabricated, which benefit from easy tunability on CCT.
This current work is considered to promote the development of Cu NCs as low-cost and
environmentally friendly phosphor candidates for lighting.