Hydrothermal / Solvothermal Synthesis of

Nanomaterials

By
Dr.G.Ramalingam
Assistant Professor
Department of Physics
E-mail:ramanloyola@gmail.com
https://scholar.google.co.in/citations?user=I9TsAbIAAAAJ&hl=en
 Hydrothermal / Solvothermal Synthesis of
Nanomaterials
Content
• What is hydrothermal / solvothermal synthesis?
•What is the main characteristics of Hydrothermal /
Solvothermal synthesis?
• Advantages & Application
•Summary
•Examples synthesis of nanomaterials via
hydrothermal / solvothermal method
 BRIEF HISTORY OF THE SOLVOTHERMAL
CRYSTAL GROWTH OF LARGE SINGLE CRYSTALS

The history of the solvothermal Crystal Growth is closely related to

the hydrothermal crystal growth of α-quartz.
due to:
→ its piezoelectric properties (leading to important applications)
→ its low temperature domain of stability
(Tα-quartz → Tβ-quartz = 573°C) (impeding the use of conventional
Crystal-growth processes)

→The elaboration of α-quartz single crystals was the first example

for industrial developments of Hydrothermal Crystal Growth.
Diamonds, quartz , piezoelectric crystal are made by hydrothermal method
 SOLVOTHERMAL PROCESSES: FROM NOVEL MATERIALS
TO HYBRID NANO-SYSTEMS.
SOLVOTHERMAL REACTIONS

A “solvothermal reaction can be defined as a chemical

reaction (or a transformation) between precursor(s) in a
solvent (in a close system) at a temperature higher than
the boiling temperature of this solvent and under high
pressure”

→ autogeneous pressure or imposed pressure.

→ Subcritical or supercritical domain.
→ Homogeneous or heterogeneous system.
 SOLVOTHERMAL PROCESS
The term « SOLVOTHERMAL » was proposed at the beginning of the
90’s (G. DEMAZEAU et al.) during the development of non-aqueous solvents.
Examples.
⇒ Synthesis and crystal growth of nitrides using liquid ammonia (NH 3) as
solvent → ammothermal process !
⇒ Synthesis and crystal growth of Fe3O4 as small single crystals using C2H5OH
as solvent → alcoholothermal process…!
Consequently each solvent can lead to a specific « word » for different
processes characterized by the same features.
SOLVO – THERMAL
Solvent use of the temperature

7
 New Trends in Solvothermal Crystal Growth Processes

MAIN FACTORS GOVERNING THE SOLVOTHERMAL CRYSTAL GROWTH

- nature of the solvent,

CHEMICAL FACTORS - nature of the nutrient,
- nature of the seeds,
- the interactions solvent/ wall of the HP. Vessel.

- the crystal growth temperature (Tgrowth),

- the ∆T value,
PHYSICAL FACTORS - the pressure value,
- the hydrodynamics in the crystal-growth system.

- the kinetics of dissolution,

- the kinetics characterizing the diffusion of chemical
species,
KINETICAL FACTORS - the crystal growth kinetics,
- the duration of the crystal growth.
 New Trends in Solvothermal Crystal Growth Processes

SOLVOTHERMAL PROCESS FOR GROWING

LARGE SINGLE CRYSTALS
Two different domains:
⇒ Crystal growth of oxides

•α-quartz (for its piezoelectric properties),• AlPO4, GaPO4, GaAsO4 (α-quartz-like

piezoelectric materials)
• calcite CaCO3 (optical properties: birefringence and transmission over a wide
spectral range)
• ZnO (wide band gap semiconductor, transparent, dielectric and
piezoelectric properties…)
• some others oxides as: KTiOPO4 (KTP), hydroxyapatite Ca10(PO4)6(OH)2, LaPO4, γ-
LiBO2, β-BaB2O4, RVO4 (R=Y, Gd), KBe2BO3F2 (kBBF), ZrW2O8, α-Fe2O3 Zeolites
(crystalline aluminosilicates containing pores and cavities of molecular
dimensions used as sorbents catalysts, ion exchange materials…)
9
 SOLVOTHERMAL PROCESS FOR GROWING
LARGE SINGLE CRYSTALS

⇒ Crystal growth of non-oxides

During these last years, strong efforts have been done for
controling the solvothermal crystal growth of GaN using a process
derived from α-quartz and ZnO solvothermal crystal growth.
Ref. “Prospects for the “ammonothermal” growth of large GaN
crystal”
T. FUKUDA, D. EHRENTRAUT J. Cryst. Growth. 305, 304-310 (2007)

Such efforts are supported by the existing or potential

applications of GaN (opto-electronics, high frequency-high power
electronics, fast-speed communication…)
10
 SOLVOTHERMAL PROCESS and CRYSTAL GROWTH

→ The crystal growth of materials as nano-particles.

As the size is reduced to the nanometer range, the material
exhibits specific properties due to quantization effects
[H. GLEITER Mater. Sci. Program. 33, 233 (1989),
Y. XIA et al. Advanced Materials 15, 353 (2003)]

In such a case the morphology plays an important role

(0D,1D,2D)
 New Trends in Solvothermal Crystal Growth Processes

THE SOLVOTHERMAL PROCESSES AND

THE CRYSTAL GROWTH AT THE NANOSCALE
Recently one-dimensionnal (1D) nano-structures (wires, rods, tubes…) have been the
focus of intensive research owing to their applications in mesoscopic physics and
fabrication of nanoscale devices.
The formation of a 1D nanostructure depends on two steps:
- the nucleation,
- the crystal growth.
In addition for generating nanostructures three main parameters must be controled:
→ the dimensions,
→ the morphology,
→ the monodispersity (or uniformity)

12
 THE SOLVOTHERMAL PROCESSES AND
THE CRYSTAL GROWTH AT THE NANOSCALE

Schematic illustrations of the different strategies for achieving 1D growth.

growth

A)→ Induction of 1D morphology through

the anisotropic structure,
B)→ confinement by a liquid droplet in the
liquid/solid process,
C)→ use of templates,
D)→ use of capping agents able to modify
the growth rate in one direction,
E)→ self assembly of OD nanostructure,
F)→ size reduction of 1D microstructure.

Y. XIA et al. Adv. Materials 15

(2003) p. 353-389

13
 CONCLUSIONS

• To open a route through new « soft chemical processes»

Kinetically controlled for stabilizing metastable systems.
• To help the synthesis of specific structures using templates.
• To control the nucleation/ crystal growth processes for the
preparation of nanocrystallites well defined in size and
morphology.
• To facilitate ,through the improvement of the chemical
reactivity and the development of mild temperature
conditions, the synthesis of hybrid nano-systems.
• Mass production of samples
 CONCLUSIONS

All the objectives of SOLVOTHERMAL PROCESSES

require to optimize :
(i) The physico-chemical properties of the precursors,
(ii) The physico-chemical properties of the solvent,
(iii) The thermodynamical parameters P, T.

Solvothermal processes appear to be important in the near

future, not only for developing Basic Science
But also
for developing new industrial processes in mild P,T conditions.
 SOLVOTHERMAL SYNTHESIS AND
CHARACTERIZATION OF
SEMICONDUCTOR NANOPARTICLES
OF CdSe AND CdSe/ZnS, CdSe/ZnSe
AND CdSe/CdTe NANOCOMPOSITES
 Objectives
 The preparation of semiconducting CdSe nanoparticles along
with nanocomposites of CdSe/ZnS, CdSe/ZnSe and CdSe/CdTe
by low temperature solution route.
 N2H4.H2O, NaOH, CTAB and L-Cystiene were used as capping
agents to optimize the experimental conditions suitable for
mass production.
The as prepared nanoparticles were characterized structurally
and optically using
–
Powder X-ray diffraction (P-XRD)
–
Scanning electron microscopy (SEM) Structural study
–
Energy dispersive X-ray analysis (EDAX)
–
Transmission electron microscopy (TEM)
–
UV-Vis spectroscopy and
Optical study
–
Photoluminescence (PL) studies
• The synthesis procedures and results of the characterization of these
nanoparticles were discussed in detail.
 High luminescence

II-VI

CdSe 0D

QDs

1.74 eV 1D
Nano rods, Tubes,
Wires, Belts
SYNTHESIS AND CHARACTERIZATION
OF CdSe NANOPARTICLES
 EARLIER WORKS
Methods Results

Oriented attachments Length 34 nm

(TBP) (Manna et al)
Reverse micelles assisted 43 nm diameter
hydrothermal
AOT, N2H2.H2O
(Lifei Xi et al)
SLS (Lian Ouyang et al) 30 nm diameter

Solvothermal method 25 nm dia, 82 nm in length

(present method )
 3.08 gm of Cd(NO3)2.4H2O 0.86 gm Na2Se

N2H4.H2O

N2H4.H2O+NaOH
POWDER X-RAY DIFFRACTION PATTERN OF CdSe
 a(Å) 4.218 Å

b(Å ) 4.218 Å

c(Å ) 6.887 Å

α(deg) 90 °

β(deg) 90 °

γ (deg) 120 °

Crystal system Hexagonal

(Wurtzite) JCPDS 77-2307
 TEM/HRTEM Analysis

Good shape with less pronounced stacking faults, with their

measured values of mean diameter and length of 25 nm and
82 nm respectively.
 HR-TEM

Lattice fringes of single nanoparticle of CdSe

SAED & EDAX Pattern
 CdSe Nanobelts (NBs)

Width of the nanobelts (NBs) 12-15 nm

Fig c & d lattice fringes of single nanoparticle of CdSe nanobelts and
SAED pattern of CdSe
 2

Fig . Schematic diagram of 1D nanostructure formation

 UV-Vis-NIR Spectrophotometer

4.5
CdSe NBs

4.0

Absorption (a.u)
3.5

3.0

2.5

2.0

200 400 600 800 1000 1200

Wavelength (nm)

CdSe NRs the absorption edge (λe) 700 nm CdSe NBs the absorption edge (λe) 695 nm
 Photoluminescence spectrum

NBs
NRs

The emission peak observed at 703 and 700 nm for NRs &NBs

Blue shift of 27 and 30 nm.

Bulk wurtzite CdSe 730 nm [Wang et al (1999)]

 CONCLUSION
• CdSe nanorods/nanobelts have been synthesized by the
solvothermal method with better control over the
morphology and crystalline quality
• The particle size and morphology were examined by powder
XRD and transmission electron microscopy (TEM).
• From the optical absorption studies (UV) the cut off
frequency is 700, 695 nm.
• The UV and PL spectrum Blue shift in emission was found
for CdSe NPs compared to bulk material.
• This study opens up new avenues for research to find
suitable experimental conditions and the possibilities of
using different reducing and complexing agents to bring out
better control over the size/morphology of the
semiconducting nanoparticles.
SYNTHESIS AND CHARACTERIZATION
OF CdSe/ZnS NANOPARTICLES
Synthesis of CdSe/ZnS
 Results and Discussion

(002) CdSe
(100) ZnS
14000
Intensity (arb.unit)

12000

(101) ZnS
10000

(110)CdSe

(201) CdSe
(103) CdSe
(110) ZnS
(102) CdSe
8000

(203) CdSe

(205) ZnS
(204) ZnS
6000

4000

2000

0
10 20 30 40 50 60 70
Two theeta
Figure . Powder X-ray dirffraction of CdSe/ZnS nanocrystal

Wurtzite hexagonal structure Debye-Scherrer formula

particles size =3.024 nm
(JCPDS card No:77-2307, 89-7385).
Figure. EDAX Spectrum of semiconductor nanocomposite
with corresponding signals of Cd, Se, Zn and S
 Scanning Electron Microscopy (SEM)
It clearly evident from the
images that the clusters of
primary ZnS nanoparticles are
adsorbed over the surface of
CdSe crystallites of nearly smooth
spherical surface.

Another interesting observation

is that the present methodology
favors effective control over the
particles size and shape

Fig. SEM Micrograph of CdSe/ZnS nanoparticles

Transmission Electron Microscopic Analysis (TEM)
 50

40
QD size is ranging between 2-4 nm
No.of particles

30
Average diameter is about 3.00 nm
20
Narrow size distribution.

10

0
2.0 2.5 3.0 3.5 4.0 4.5 5.0
Particles size (QDs)

Figure . Size distribution chart of

CdSe/ZnS quantum dots
 L-Cysetine play a vital role not
only functions as a stabilizer in
true system but also offers S
atoms from its gradual
decomposition in the later stage
of the synthesis.

The ring pattern- selected area

electron diffraction (SAED) is shown in
figure which confirms the presence of
QDs.
Figure . Schematic diagrams of type-I and
type-II hetrojunction band alignment Figure . Schematic illustration of
CdSe/ZnS core-shell hetrostructure type-I
 Optical Absorption Study
Figure. UV-Vis absorption spectrum of CdSe/ZnS QDs

2.4

2.2 D = (1.6122 × 10-9) λ4 – (2.6575 × 10-6) λ3 +

515 nm (1.6242 × 10-3) λ2 – (0.4277) λ + 41.57.
Absorption (a.u)

2.0
Using the above formula the average nanoparticles diameter is
1.8
found to be D=5.653 nm.
1.6

1.4

1.2 R=D/2= 2.8225 nm

1.0

0.8

495 500 505 510 515 520 525 530 535 540 545

Wavelength (nm)

An absorption peak for CdSe is expected at 716 nm.

There is a strong blue-shift in the absorption spectrum indicating that the particles must be
smaller than the Bohr radius (aB) of exciton which is 5.4 nm for CdSe (Shriwas 2005).

The as prepared CdSe/ZnS QDs size is R=2.8 nm; the decreased (R<< aB) regime indicate the
strong-quantum confinement effect (Babentson and Sizov 2008).
 Photoluminescence Study
Figure . Photoluminescence spectrum of CdSe/ZnS QDs
1.0

Absorption (λabs ~ 515 nm) suggest

0.8 monodispersity of CdSe/ZnS
nanoparticles and the narrow PL
Intensity(a.u)

0.6 emission (λemi ~ 525 nm) indicates near

band edge emission.
0.4 FWHM 15 nm

0.2

0.0
500 510 520 530 540 550 560 570 580 590 600
Wavelength (nm)

The PL emission maximum lies close to its absorption-onset indicates that the PL
emission arises as a result of the direct recombination between LUMO and HOMO
charge carriers (Kortan et al 1990).

QDs with emission in the spectral range from 516 to 538 nm are of special interest for
the preparation of QDs based green and white LEDs. So we suggest that CdSe/ZnS core
shell structured NCs are among promising candidates (Weiling et al 2008).
 Conclusion
 In the present work, efforts have been made to establish the feasibility of
NPs synthesis of amino acid capped CdSe/ZnS quantum dots. L-Cysteine
plays three essential roles: Acts as a source for sulphide ions, as a growth
moderator and as a stabilizer.

 The size of CdSe / ZnS QDs was successfully controlled by environmental

friendly solvent( L-Cystine).

 A narrower particle size distribution upon ZnS shell growth and the control
of the particle shape by symmetrically growing ZnS shell on CdSe core.

 The better controlled size of QDs provides more efficient, more stable and
luminescence spectral region used to generate green and white LEDs.

 The as prepared CdSe/ZnS potentially lower toxity by non- toxic ZnS shell.
SYNTHESIS AND CHARACTERIZATION CdSe/ZnSe
NANOCOMPOSITE
 Synthesis of CdSe/ZnSe
CdSe

ZnSe
Se 2-

CdSe CdSe/ZnSe
ZnSe

CTAB
 Results and Discussion
(002) CdSe
140 (100) ZnSe The major diffracted planes (002), (100) and
120 (200), (103) are indicating both CdSe and ZnSe
nanocomposite hetrostructure are in wurtzite
Intensity (arb.unit)

100
hexagonal phase.
80 (110) CdSe

(200) CdSe
60 (103) ZnSe
This has been verified with JCPDS file
40
numbers of CdSe (77-2307) and ZnSe (89-
20 2940).
0
10 20 30 40 50 60 70
Two theeta
X-ray diffraction pattern of CdSe/ZnSe
nanocomposite

EDX line scanning spectrum of CdSe/ZnSe nanorod

 Scanning Electron Microscopy (SEM)

The hydrothermal synthesis temperature along with the capping reagent can influence
the nanoparticle size and morphology.

A close observation of the SEM image of the present CdSe/ZnSe suggests that the surface
of nanorods is relatively smooth and this could be attributed to the relatively high
reaction time/temperature employed.

The capping agent CTAB/ L-cysteine adsorbed different planes of the incipient
CdSe/ZnSe. The nucleation not only prevents the particles from agglomeration, but also
influences the growth of rod-like morphology.
Transmission Electron Microscopic Analysis (TEM)
• The TEM photograph shows the presence of
nanorods with a major population of prolonged
nanorods as well as a minor population of
spherical shape nanoparticles.
• The obtained nanorods have diameter in the
range 50-70 nm and the length is 150-175 nm
whereas the spherical shape nanocomposites
were achieved within 40-50 nm diameters.
• It is clearly seen that as the time of growth
increases, the spherical shape of the
nanocomposite grow towards rod-like
morphologies.
 HRTEM images of as-prepared CdSe/ZnSe nanocomposite of nanorods

The crystallinity of composite NC was confirmed by

the clear lattice fringes in Figure. Further the it
Shows the lattice fringes of a single nanorod and
clearly visible lattice plane endorses the formation.
This lattice plane can be indexed with wurtzite
structure and calculated interplaner distance is SAED pattern of nanocomposite

around 0.338 nm.

• we suggest that L-cysteine and CTAB proves the better
surface passivation of the CdSe/ZnSe crystalline lattice
under laboratory conditions.
• It is noted that thiol-capped NC containing amino
groups can be easily used for the conjugation of two
binary metals.
• During the growth process L-cysteine and CTAB plays an
important role in the transformation of spherical to rod
like morphology.
• The organic surfactant (CTAB) adsorbed by the coating
of nanorods is essential to disperse and stabilize them
in the solvent which could prevent their further
agglomeration and oxidation .
 4.0
CdSe NRs

3.5
UV-Vis absorption spectroscopy
Absorption (a.u)

3.0

The absorption cut-off frequency (λabs) of

2.5

2.0
CdSe is 700 nm and for CdSe/ZnSe is
524 nm. The increase in the frequency shift
indicates the quantum-confinement in the
200 400 600 800 1000

Wavelength (nm)

CdSe/ZnSe nanorods.

2.4
CdSe-ZnSe The blue shift confirms that the formed
material is a nanocomposite. The presence of
2.2

2.0

ZnSe on the CdSe surface decreases the

Absorption (a.u)

1.8

1.6
exaction energy which is consistent with
relaxation of quantum-confinement in the
1.4

1.2

1.0 CdSe rods.

0.8

0.6

480 490 500 510 520 530 540 550

Wavelength (nm)
 2.5x10
7
Photoluminescence Study
2.0x10
7 The present investigation confirms the blue shift in
the uncapped sample when compared to the
Intensity (Arb.Unit)

1.5x10
7
capped sample (700 nm for pure CdSe, 537 nm for
CTAB and L-Cysetine capped CdSe/ZnSe).
7
1.0x10

6
At the same time, we also observe minor
population of spherical nanoparticles in the
5.0x10

0.0
ensemble which could be seen by the minor peak
650 660 670 680 690 700 710 720
at 520 nm in PL spectrum.
Wavelength (nm)
3.0
537 nm CdSe/ZnSe
Further the PL and absorption spectral study
support the view that the nanocomposite are
2.5
Intensity x 10 (a.u)

2.0 predominantly nanorods at λem ~ 537 nm.

5

1.5
The fact that the PL emission maximum lies close to
1.0
520 nm its absorption-onset indicates that the PL emission
0.5
arises as a result of direct recombination between
LUMO and HOMO.
0.0
500 510 520 530 540 550 560 570

Wavelength (nm)
02/06/15 05:08 AM
 CONCLUSION
• The CdSe/ZnSe composite nanorods were successfully
synthesized by using bio capping agents L-Cysetine and CTAB.

• The wurtize-hexagonal morphology was verified by powder

XRD and SAED Pattern. The EDA confirms the presence of Cd,
Zn, Se metal in the as prepared nanorods.

• It has been demonstrated that the energy of the band-edge

luminescence can be readily tuned by adding the ZnSe
overlayer. This study opens up new avenues for research to
synthesis L-Cysetine and CTAB bio-capsulated composite
nanorods.

• This semiconducting nanorods has the potential for the

application of solid-state lighting and molecular bio-imaging.
02/06/15 05:08 AM
Synthesis and Characterization of
CdSe/CdTe Nanorods

02/06/15 05:08 AM
 Objectives
 We describe the synthesis of CdSe@CdTe QDs
by simple hydrothermal technique without using
TOPO solvent.

 TEM consistent the quantum dots size is 12 nm.

 Optical absorption and photoluminescence (PL)

measurement as well as EDX demonstrated good
quality of QDs obtained, the peak becomes blue shifted.

 We have succeeded a cost effective method to produce

CdSe/CdTe QDs unlike the previous researches.
65
 Synthesis of CdSe/CdTe

4NaBH4 + 2Te + 7H2O 2NaHTe + Na2B4O7 + 14H2O

2NaHTe + 2Cd (NO3)2.H2 2CdTe↓ + 2NaOH + H2O + N2O↑

1.216 g of L-Cysteine
o The autoclave was sealed and heated at 200 °C for a reaction 6
hrs.
o The obtained CdSe/CdTe precipitate was separated by centrifuge
and its impurities were removed by repeated washing with water,
ethanol and methanol.
o The final composite was annealed at 80°C for 3 hrs. 66
 Results and Discussion
600
 The diffraction peaks at 24.20°,
CdTe (100)
590
27.60°, 42.27° and 56.94° are

CdTe (111)
580

CdSe (002)
Intensity (arb.unit)

570
assigned to the (002) (101) (112)
560 and (002) planes of hexagonal
550 CdSe (101) phase.

CdTe (220)
CdSe (112)
CdTe (211)
540 The intensity of four major

CdSe (002)
530 peaks for cubic CdTe namely, (100)
520 (111) (211) and (220) planes are
510
positioned at 13.69°, 24.20°,
70 35.37° and 39.85° respectively.
500
5 10 15 20 25 30 35 40 45 50 55 60 65
Two theeta
The diffraction peaks can be
Fig. XRD pattern of CdSe/CdTe QDs
indexed to the mixed hexagonal
and cubic CdSe/CdTe composite
with L-Cystine capping legand.

The observed data are in good agreement with the literature values
(JCPDS No: 89-3011 (CdTe) and 77-2304 (CdSe).
67
 TEM Analysis

Fig. Size distribution chart of CdSe/CdTe

quantum dots
25

TEM can identify clearly the shape and size of QDs. 20

Numberof Particles
It is interesting to note the presence of highly
15

10

monodispersive and nearly spherical core-shell QDs . 5

A closed examination of figure shows the absence of 10 11 12 13 14

Particles size distributation (nm)
15

agglomeration to a large extent in the CdSe/CdTe

QDs synthesized via water soluble L-Cysetine amino
68
acid.
 Fig. HRTEM images of CdSe/CdTe core/shell QDs

Fig. SAED pattern of CdSe/CdTe QDs 69

Fig. EDX spectrum of CdSe/CdTe QDs
 Optical absorption & Photoluminescence study
2.2 544 nm
535 nm
2.5

2.0

2.0
1.8
Absorption (a.u)

intensity (a.u)
1.6
1.5
1.4

1.2 1.0

1.0
0.5
0.8

0.6 0.0
500 510 520 530 540 550 560 570 490 500 510 520 530 540 550 560
Wavelength (nm)
Wavelength (nm)
Fig. PL emission spectrum of L-cysteine capped
Fig. UV-visible absorption spectrum of L-cysteine CdSe/CdTe QDs
capped
CdSe/CdTe QDs
The sample shows excitonic peak at 535 nm. Figures suggests manodispersity of
CdSe/CdTe and the narrow PL emission at λemi ~ 544 nm indicates near band edge
emission. The fact that the PL emission maximum lies close to its absorption onset
indicates that the PL emission arises as a result of direct recombination between LUMO
and HOMO charge carriers.
One Bohr radius (aB) of CdSe and CdTe is 5 and 7 nm respectively. The as prepared
CdSe/CdTe QDs size is R=12 nm, the decreased (R >>a B) regime indicates the weak-quantum
confinement effect 70
 CONCLUSION
The XRD and TEM results suggest that the size of spherical
CdSe/CdTe core shell QDs is 12 nm.

Further SAED pattern resembled the mixed hexagonal, cubic

structure crystal system of core-shell nanoparticles are
obtained .

The absorbance of characteristic QDs revealed the weak

Quantum confinement effect of the charge carriers in the core
shell crystals system.

The PL emission of the resulting type II QDs was found to be

significantly higher than that of the CdTe/CdSe core/shell.

71
 Summary
Materials CdSe CdSe/ZnS CdSe/ZnSe CdSe/CdTe
Name
Shape Nanorods, Quantum Nanorods Spherical
nanobelts dots (QDs) nanoparticles
Size Dia 25nm, 2.82 nm Dia 50-75 nm 12 nm
length 82 nm Length 150-175
12-15 nm with nm
Capping N2H4.H2O, L-Cysteine L-Cysteine , L-Cysteine
ligands N2H4.H2O+NaOH CTAB
Structure Wurtzite Wurtzite Wurtzite hexagonal
(phase) hexagonal hexagonal hexagonal and Cubic
Uv (λabs) 700, 695 nm 515 nm 524 nm 535 nm
Pl (λems) 703, 700 nm 525 nm 537 nm 544 nm
Application Solar cell, Bio- green and Solar cell, Bio- Solar cell,
Medical, white LEDs Medical, etc ., Cancer
02/06/15 05:08 AM
nanoelectronics treatments
 Future work
Different synthesis routes, The preparation of
thin films

Varying calcinations temperatures, pH,
pressure,different concentrations of the involved
surfactants /modifiers

Nanoparticles are to be coupled with quantum

dots to fabricate QDs sensitized solar cell, nonlinear
optical, optoelectronic devices and bio-
medical labeling.
THANK YOU FOR YOUR ATTENTION.