Jaro 2021 C9906
Spektroskopické metody charakterizace nanomateriálů
1. Spektroskopie multifunkčních koloidálních nanostruktur
- reprezentativní strategie kondenzace polymérních a nanočásticových solů
- příklady spektroskopického pozorování fyzikálních a strukturálních vlastností
2. Polovodičové nanočástice v elektrotechnickém sektoru (ZnO, „CdZnSSe")
- Transparentníplanární elektrody
- Elektrochromie
- Elektro/fotoluminescencí systémy
3. Ti02 v solárním nanosektoru
- Úvod do solární technologie
- Nanofotokatalytické systémy
- Nanofotovoltaika
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Chemické inženýrství anorganických nanokoloidu
Multiparametrální syntézy: Cíl: Monodisperzita, stabilita, bez toxicity, jednoduchou cestou
Prekurzor I + Ligand
Komplexace
Prekurzor II + Ligand
Dopovací prvky
Nukleace/Zrání
Modifikace povrch/interior
2
Čištění
Voda/Etanol/Koordinační solventy (- 40°C < T < +360 °C)
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Multifunkcionalita
H L-CD
Bi-funkcionalita
Jádro/Slupka co-dopovánŕ
El. náboje
Stabilizátor
Sol-gelova Nanochemie
1. Molecular bottom-up approach
2. High homogeneity of multi-atomic compositions
3. Macroscopic property tuning on the molecular scale
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Komplexace alkoxidů
Snížení reaktivity a protekce vůči srážení
Chelating Agents
R R
j**
I
M M
\ /
M
Carboxylates
R o
y
\ /
M
R .O
y
I
M M
Sulfonates
R
R1'
vr
M
J
1 ? I
M m M
p-Diketonates  a-Amino- Phosphonates carboxylates
M(OR)n
R-( M(OR)n,
M = V, W, Sn, Ti, Zr, Ce, Al, Y, Zn,...
hydrolýza & kondenzace
X5 ti
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Strategie organizace nanočástic na substrátech
ii(OEt):
Tvorba tenkých vrstev
• dip-coating
• spin-coating
• spray
• Doctor Blade
Sol
vrstva
Spékání Fotolitografie
Adhéze ! Kovalentní vazby Elektrostatické spojení
(0
E
co i-
o
(X: SH, NH2, COO)
X-
i-+->
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n
3
w
> o
> o
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Kontrolované ponořování/tažení substrátu
(ongl. dip coating)
Solgelway Paris
Landau- Levichova teorie:
e[jim] =
0,94(n vt)% (Tai^-iP-g^
e tloušťka vrstvy
rj dyn. viskozita
Ygi napětí fázového rozhraní
p hustota roztoku
g gr. zrychlení (9,806 m/s2)
vt rychlost ponoru
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Centrifugální pokrytí:
Roztok na rotujících substrátech, angl. Spin-on coating
a)
\
0
55 55
1 +
4 • p • co2 • e\ • ř 3-/;
e tloušťka filmu
e0 počátková tloušťka
r| dyn. viskozita
co rotační rychlost substrátu
p hustota roztoku
t doba rotace
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mobile substrates
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fs-Laser Printed Freeform 3D Structures
Laser source: 100-400 fs, MHz-kHz SHG g)->2g) initiates 2PP (340 nm - 540 nm)
ective
Sub-100 nm voxel
S. Steenhusen, R. Houbertz FhG, ISC, Wurzburg, Germany
Fraunhofer
ISC
Low NA focus
auditory ossicles human middle ear
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Targets: Life sciences Energy sector ICT sector
100 um
FhG ISC Würzburg
mm
W/Mt}
♦AtAtAtA?
Nanoscribe GmbH Karlsruhe
Analytic methods employed to study structural evolution in the sol-gel process
NMR, FTIR, Raman, SAXS
Nomenclature and chemical shift in 29Si- and 31P-NMR
R,Si-OSi
M1
D°
OSi
Ro-Si
OSi
R —
D2
OSi-
Si-OSi-
I
OSi-
T°
T3
Q°
OSi-■SiO — Si— OSi-OSi-
0/
-20
-40
-60   ppm -80
-100
-120
Control questions:
2. Structural formula of the Si-Q2 state?
3. Structural formulas of X° states (X: M,D,T,Q)?
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Application of 29Si - NMR
H,0
TEOS
R
TO
OX
xo—Si — ox
1
/
-1-,—i   i l
X = OCHjOrOH
R = organic part of ihe precurBsr
-40        -45        -50        -55        -00        -85        -7D -75
Condensation degree
OEt	OSi
EtO - Si - OSi	SiO - Si - OSi
OEt 1	OSi
Condensation degree
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NMR-Spectroscopy of ZnO co-doping
OSi w -80   -90 -100 -110 -120 -130
O - Si - OSi
OSi
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FTIR characterizations
Group	A (cnr1'	Observations
Si-OH	3700-3300	streching Si-O-H
	955-835	streching Si-0
	982-950	bending Si-O-H
Si-O-Si	1090-1020	streching Si-O-Si
	800-730	bending Si-O-Si
Si-O-CH3	-2860	streching -CH3
	- 1190	CH3 rocking
	- 1100	streching Si-O-C
	850-800	streching Si-O-C
H20	3600-3100	
	1640-1615	
C02	2349	
HO - Si - O - Si
(OCH3)2
TMOS/EtOH/H20, pH 4,9
Si-OH
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					1	l\i	IC					1							
												■A	\						
															c	;i	■0-		s
2400        19DD        1400        900 400
[1/cm]
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monodentate bridging bidentate chelate bidentate
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Raman spectroscopy in sol-gel process
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IR
Raman
reaction vessel
magnetic stirrer
Nd-YAG, Ar, TiS,...
b)
laser
microscope optics
substrate
PC
laser
CCD
spectroscope
CCD
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TEOS/THF/water/HCI
GPTES/APTES/water
Si-OEt
Si-O-Si   stretching EtOH
. " ".. formation stretching
Si-O-Si bending
200 400 600 £00 1000 12001400 1600 1S00 7000
Raman shift [cm1]
Y: Epoxy group Amine group
NH2 douplet streching (as, s)
f\ native
\ dilution
öjl + water
11QQ 3150 320Q j?W 33CM1 3350 3400 3450 3500 Raman shift [cm-1]
What happened?
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Small Angle Scattering
Rg - gyration radius
(primary particles and aggregates)
Vp- pore and particle volume
mp- particle mass
A - specific surface area
Df-fractal dimension
Shape of primary particles and
aggregates
Dilute particles
Crowded particles
Random porous/2 -phase
Liquid crystalline
		
		
		mmmmm
		a.   Lamellar [L J
Orientation and self-organisation
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Hydrated DNA
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log scattering vector
Fig. B2. Small-angle scattering curve for a disordered particle network. All structural features appear in the corresponding regions of scattering vector q. R and r denote a mean cluster ana particle size, respectively; exponents D and Ds, determining a power-law decay, are a measure of the morphology of network aggregates and particle surfaces, respectively.
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I (Q)
104
SANS of silica aerogels
10-1
	1/R
	D = 2,1
37,9	1/r
47,9	
53,1	
64,8 kg/nP	
75,8	
101,0	
135,7	
10-3
"i "i ij
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Q (l/Á)
i—íl i i i j
10~i
Note:
masse ~ RD
Euclidien objects D = 3
Mass fractal objects 1 < Df < 3
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1 Chapter, revision
1. What are the principal molecular precursors of the sol-gel process used to elaborate glasses, ceramics and hybrid composites;
2. To transform Ti(OC3H7)4 into polymeric heterosol containing "Zn-O-Ti" moieties,
Zn- acetate dehydrate is used. Hereby, an isopropanolic reactants mixture is refluxed during several hours;
Give the principal chemical reactions taking place in the reaction mixture;
3. Using FTIR, various surface states of carboxylates can be identified; explain how?
4. Interpret the previous Raman data of the GPTES/APTES/water reaction mixture
5. How the Si29 NMR spectrum would look like in the case of a complete TEOS condensation?
6. Explain the usefulness of the Porod region in the experimental SAXS and SANS data? (see the log I — log Q plot)
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(5) Photoluminescing nanoparticles
- Spectral profile and quantum yield of photoluminescence
- Chemical activation strategies (« core-shell», lanthanide doping, FRET)
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solid/liquid
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Note:
Av|/    = energy barrier at the interface (> 100 nm)
EgaP   = §aP energy varies with size
jfe> SFermi= Fermi level (eV)
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_±_
anode
cathode
Note:
Surface chemistry, nanoporosity And size are the key parameters
Figure of merit ~ T / Rs
T = optical transmission (UV : 400-900 nm) Rs = surface (sheet) resistance (< 20 Q)
macro
Large specific surface area!!
w
7and Rs are controled by :
Morphology (porosity, degree of crystallinity) Surface chemistry (traps, oxidizing agents) Defects - intrinsic and extrinsic Doping ionic/cationic
Sciences Chimiques L ""S3 de Rennes
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Rs   = p / e = 1 / q ne |i t
Rs: sheet resistance (Q/D)
p: electyric resistivity (Q cm)
t: film thickness ( < 2 |iim)
ne: number of free electrons / cm3
\x: electron mobility (cm2V1s"1)
q: elementary charge
N \x q = conductivity (Q_1 cm1)
H20.
H +OH"
10
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23
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S    Sr GaAs
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10
100
1000
Electron Mobility, (cmVV1)
t|i via morphology & surface chemistry
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0.3   0.5 1 2     3       5 10        ?0   30 50
Wavelength {jiml
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Elaboration methods
Pulsed Laser Deposition Sputtering
Sputter cathode
/-Vacuum chamber
-
- Unhealed glass Sputter plasma
Spray pyrolysis
SPRAY PYR0LYSIS
Spray nozzle Aerosol
!/ _
o o ó i o o o/cni J o u
^    Heated glass
Soft chemistry
Metal alkoxides
H&C       dip/spin heat
—► Sol-* Gel -► Films
source
polymeric
OO
o°
particulate
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nano-ZnO
JACS 1991, 113, 2826
EtOH, 90°C
4 Zn(Ac)2-2(H20)   <z>   2 H Ac + 7 H20 + [Zn40](Ac)6
(T) nanoparticulate 2.5 n m < taille < 5 nm
polymeric taille < 1 nm
[Zn40](Ac)6
Zn(Ac)22(H20) 2-aminoethanol
LiOH-HoO
Zn-Ac
•   ■» ■ ln.tltuld™)
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AZO electrode via sol-gel (ZnO/AI3+)
3500      2500      1500 500 Wavenumber [cm1]
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(Zn40)Ac
OH'
w Post-condensation:
F    1. Pore filling
2. Elimination of 02, H20 1
A Creation of conducting € ^^channels "
nD ~ 2.1 |i = 9 cm2/Vs
nD = refractive index (ZnO bulk: = 2.1)
	100
	80
	60
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	20
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0.5   1.0   1.5   2.0   2.5 3.0 M|im]
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H CE = coloration yield (optical efficiency) A O.D. = optical density change (contrast) Q = injected charges (C/cm2)
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i Sciences Chimiques
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Ni(OH)2       NiOOH + H+ + e"
NiO + Ni(OH)2      Ni203 + 2H++ 2 e"
green to brownish
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Electrochromic cells design (global overview)
glass or plastics
+ 1-4V
inserted electrode
®
Molecules Nanoparticles Org. Conjugated Polymers
Key parameters:
Engineering of electronic and ionic transport Life time: 104-105 cycles (5-20 ans) Coloration/decoloration dynamics - ms, sec, min Temperature: -50'Xtill + 100°C Optical transparency of multilayers
inserted electrode
H+, Li+, Na+
glass or plastics
Ionic Conductors:
Gels, membranes, organoceramics
- Zr02, Ta205
- Organic-inorganic hybrids
- polyelectrolytes: PEO, PVA
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II
Viologenes (methyl-, ethyle-) at the Ti02 NP's interface
MV
gj 60
£ to c
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400       450       500       550       600 650
Wavelength (nm)
700
-1	1 j.	Catalyzed electrochromy		
-1	1 P-			
r 0 OCT	Ti02/MV2+ <-	Redox pair r h L i J 1—Li+	© OCT	
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TiOo/MV2+ + Lil
Ti02/MV + + e- + Li+ + I2
bleached
darkened
Thin film technologies
1. rf-sputtering
2. CVD (molecular precursors of W, Nb, Ti)
3. Sol-gel
- WOfOEtjj, W02(OEt)2
- W/H202/(COO)2
- Nb(OR)5
- Ti(OR)4
- Ni(Ac)2 4H20/MeOH/dimethylamlnoethanol
Pilkington, St Gobain, Daimler Chrysler, Renault, Toyota, Skoda etc...
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Vö^f v&c
anode
EL- Figure of merit
Hel — Tel ' ^photons ^ ^el,injected
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Global design of hybrid cells for intersectorial applications
cathode ^NjJ-n - diode (plastics)
anode
PPV
p-SC	
6 \	1
	T
	SOj Na+
Q Nanoparticles and plastics
PEDOT = poly-(3,4-ethylenedioxythiophene) PSS = poly( styrene sulfonät) PPV = poly(p- phenylene vinylene)
Luminophors et conductors p or n
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CdS, CdSe, ZnS, CdTe, ZnTe,
Silicium, Carbon! etc...
Cations 77? (III): Er, Yb, Tm ZnO, CdSe, NaYF4
Silica, Au, Ag Organic chromophors (Er, Yb)@NaGdF4
Sciences Chimiques ŕ ""SS de Rennes
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o< 0,1%
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Life time of charge carriers in SC-NPs
5 -10 nm
lumiere
1 fs
10 100h
1 ps
Recombinaison thermique
NP
1 ns
Note:
Blocking of ultrarapid thermal recombinations is needed
1 |IS
logt    Duree de vie-T
I
1
JH Recombinations/Relaxations of charge carriers
SC-NP's Luminescence
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7/
%     lanthanide doping
I
Luminescence Activation via « core-shell »
Spatial charge separation
Note:
1. Choice of SC-couple
2. Shell nanochemistry (epitaxy, strong chemical bonds)
Nanocomposites "Core-Shell" CdS-M(OH)2
Cd(CI04)2/H2S/H20
NaOH
M(CI04)2 (M:Cd, Zn)
M(OH),
acivated
0,5 0,4 0,3
E
2 0,2
Q
d 0,1
Absorption
Lumineszenz
.türkis
300 350 X [ nm ]
JACS 1987
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Core-shell activated luminescence
TOPO Cd(CH3)2
Se (s) + TBP (I) Se=P(C4H9)3
360°C
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i Sciences Chimiques „ £   r-"a de Rennes
1IMJ
rCdSe^
Se2- M „ Cd2^
(Me3Si)2S/Ar Zn(CH3)2
TOPO: O = P(C8H17)3
HS-C12H25
Hydrophobic, soluble in toluene !!
CdSe Quantum Dots  (Bavendi Group)
ííflll
Bawendi et al, MIT; Alivisatos et al, Berkley
L. Spanhel
Q Lanthanide doped Nanoparticles (Ln(5)NP's)
Figure of merit ~ NLn (cm3) t (ms) T (%) / n (pph0non)
1. NLn = 1020 - 1021 Er3+/cm3
2. t = life time of luminescence
Er3+: 10-25 ms
3. Film transparency
4. Luminescence efficiency (phonon energy!)
Luminescence efficiency
Wr + Wnr   Wr + AeBp
Wr = probability of recombination (radiative) Wnr = Probabilitě de la recombination (non-radiative) p = number ofphonons bridging the fundamental gap A,B = empirical constantes
11/2
13/2
15/2
A savoir:
Phonon = elastic waves produced by collective atomic vibrations
Multi-phonon Relaxation
Energy Transfer (Dexter) Er - O - Er
-gap
1.54 jim
1.54 u.m (0,8 eV) = 6537 cm1
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p = A E/ n oj = 6537 cmV n oj
Vibration	nw (cm-1)	p - phonons
O-H	3000-3500	2
C-H	2800	2-3
P-O-P	1300	5
Si-O-Si	1000	6
MxOy MxChalcy	300-800	8-20
fluorides	200-400	15-30
Note:
To maximize the fluorescence intensity
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1. Avoid Ln- ionic agregations
2. Avoid high energy phonons (OH, CH)
Multiphonon relaxation in ethanolic nanocolloids
11/2
13/2
15/2
1.54 urn
Er3+
u c
U
O 3
Er@CdSe 1,7 nm clusters
Er@ZnO 5 nm nanocrystals
Er-@APTES mplexes
1400
1500 1600 1700
A, [nmj
■.....A)
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Local networks
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Er,Si-co-doping" of nano-ZnO
Zn(OAc)2 in 1-Propanol
Me4N-OH
5-10% TEOS
1-10 at.% Er(OAc):
2-3 M Er,Si@ZnO-Sol for dip coatings
u c
Qi u
s_ O 3
E E ^>
Er3+,Si4+@Zn0 1	
waveguide \	
	\ t ~ 10 ms
~i-I-i-r
1460
1500
1540
1580
1620
I IMI % Sciences Chimiques W ^7;deRenvn&ecS L. Spanfte/
Highly Efficient Multicolour Upconversion Emission in Transparent Colloids of Lanthanide-Doped NaYF4 Nanocrystals**
By Stephan Heer. Karsten Kämpe. Hans-Ulrich Giulel, and Markus Haase*
Adv. Mater. 2004
LnCI3 6H20, Ln : Y, Yb, Er, Tm in methanol
Ligand!
NH4F
DMSO Chloroform
NaYF4/Ln
NaYF4/Ln
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7: Sciences Chimiques * L~~ďeRennes
ř v&c
Q Nanoparticles = Carriers and Activateurs of FRET
FRET = « Forster resonant energy transfer »
Critical parameters FRET:
Donneur Accepteur
Ex Em
Em
AAA
Longueurs d'ondes (nm)
B
1.0
0 0,6
15
1 0.4 111 02
0.0
o
R < 10 nm
R-6
E = ■
—r-i-1-1-1
0     2     4     6     8 10
Pin lie FRET
J g
R » 10 nm
Distance (nm)
I'm ,k l/itl
Angle t 30° Angle - 90°
Wikipedia
s Sciences Chimiques £   L "■•»; de Rennes
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ML
Nanoparticules de NaGdF4dopees par Er3+et Yb3+ pour l'upconversion de la luminescence
shell: NaGdF4-Yb
rS/2
core: NaGdF4- Er3+, Yb3+
r9/l
«I 1
■ll/l
'13/2
Tin Yb5' Shell
'is/2
£ IUI % Sciences Chimiques # ^7"deRenvnsecS ^     L. Spante/
Er34 Yb3*        Yb3' Yb3,
Core
Er3«
Yb3* Shell
Vetrone et al, Adv. Fund. Mater. 2009
Blue Emission
reen Emission
Red Emission
Wang&Tang, Nanoletters 2006
Greffage de trois chromophores organiques en tandem sur les NP de la silice
xqv = 480
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Wavelength {nm)
Chapter 2. Revision, questions:
1. Explain energy diagram differences between macro- and nanoelectrodes in contact with
electrolyte
2. Knowledge of crucial phys. parameters governing the performance of TCO electrodes
3. Strategy of controlling mobility and concentration of free electrons
4. Describe the component design and chemical composition of catodic and anodic electrochromy device
5. What are the competing processes taking place in photoexcited semicondutor nanoparticles?
6. What are the strategies of photoluminescence activation?
7. Explain the energy diagramme of strongly luminscent SC NP's
8. Explain the close relation between photovoltaics and electroluminescence
9. What are the crucial parameters of lanthanide based luminescing devices?
Instltutdesl
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Veselovskii & Shub 1952
1839
Fujishima & Honda 1972
[nO
	colloids	
id		
° o° 8 o o ° ° °0 ° _ ° Q,		
J
membranes
H202
H20
microcristaux micropoudres
H2 + 02
Ti02, ZnO, W03, Fe20o, CdS, ZnS,graphene, fullerenes
1954
1980
nanotechnology
History of solar technology
Phänomene photoelectrigue
1. Generation: mono-Si	
Chapin, Fuller, Pearson (USA)	2. Generation: couches minces a base de a-Si, CdTe, CulnSe2 (CIS)
3. Generation:
nanostructures, metamateriaux
7& ......As,
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Photocatalysis applications
1. Organic preparative synthesis
2. Environmental detoxification
3. Self-cleaning windows
4. Solar water splitting (solar fuels, 02, H2)
5. Carbon dioxide transformations
6. Biosystems in photocatalysis
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► spectral profile based selection
visible light active nano's are needed (400 - 600 nm)
► thermodynamics based selection
comparison of band energy levels with redox potentials
► kinetics oriented selection
heterostructures, dopings and surface modifications
► morphology of immobilized nanostructures
particle shapes, aggregate architectures and mesoporosity
► integration into photoreactor prototypes on various scales
nanocolloids, powders, thin coatings, photoreactor design
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Photocata selection :
1. Optical Gap
2. Energy levels of VB and CB
3. Photostability
4. Toxicity
5. Applications (energie/environnement/preparative synthesis
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4
-0.31
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2.18 -0.8
-0.4
2.7
2.37
1.78
SnS2 2.11
-0.90
2.89
ZnO
3.2
2.9
v2o5
2.6
1.9
ZnS
3.7
2.6
SrTi03
3.4
-0.93
-0.3
InP
1.34
-0.84
2.25
-0.48
0.5
. TaON
2.29 -0.4
AgCl 3
GaN 'J:1
3.4 -0.7
AgBr 2.6
Ni2P 1
0.8 CdSe 1.8
1.89
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2.04
2.5
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2.7
1.15
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Thermodynamics of charge carrier transfer
Photo-oxidation
Evb> E°(D/D+) !
Photo-reduction
ECB <E°(A/A) I
Ehn > Eg
Example: formation of Cu nanoislands on Ti02
1. Cu2+, NaBH4
2. Cu2+, isopropanol in water UV-
light
> +1 —	
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0 —	\ s \ \ + o,i (e",teB-Tio2) \ \
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>	i Donor
Cu2+ + 2e-> Cu° (x4) BH4" + 3 H20 -> H3BO3 + 7H+ +8 e"
BH4" + 4 Cu2+ + 3 H20 -> H3BO3 + 7H+ +4 Cu°
HoO -
H3BO3
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Kinetics and photocatalysis
Note:
10 nm
Reacting ... species
l.
2.
To eliminate the rapid thermal relaxations and recombination's is the biggest challenge
Efficient photo catalysis requires a closed contact (covalent, electrostatic) at the interface NP/molecule The best actual approach is the spatial charge separation
logt
1 fs
10 100 1 ps
1 ns
1 jus
p Recombination/Relaxation of charge carriers
Brawnian motion
fluorescence
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C02 photo-transformations via surface plasmons
Vacuum (eV) -3-
-5-
NHE (Volts) -2
-1
Fermi level of Au
COj/HCHO -0.40 v C0)CH30H -0.32 V CO,/CH4 -0.244 V
\f HjO/02 0.82 V
D. Astruc, Univ. Bordeaux RSC-Chem. Soc. Rev. 2014, 43, 7188
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reaction		
C02 + 2H +	+ 2e"	— CO + H20
C02 + 2H +	+ 2e"	— HCOOH
C02 + 4H +	+ 4c	— HCHO
CQz + 6H +	+ & "	— CH3OH
t^^O^ + &H +	+ Se"	
NO;			M-[:	
rS	OH + .1 H3C-C-CH3 H	Au/TiOj-Ag	X	0 tl + 3 H3C—C—CH3 + 2 H20
		Xe lamp {X - 450-600 nm)		
OH Au/Cc02
green LfcDs
X ^
X=N02s CI, CH3> OCH^ and NH,(
CUO
Note:
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or
NH-.
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ir
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OH
D. Astruc, Univ. Bordeaux RSC-Chem. Soc. Rev. 2014, 43, 7188
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Photocatalyse environnementale
Photo-mineralisation de polluants organiques
CxHyClz
CXHyPz
CxHyNz
CXHySZ
Super-Hydrophilie
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phosphates
nitrates
sulphates
Purification des eaux industrielles
Auto-nettoyage et sterilisation solaire Interfaces resistantes aux bacteries et virus
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Groupe OHc forme par l'action de Ti02 +UV
Micro-organismes
Contaminants decomposes en H2O/C0?/02
Groupe OH° detruisant les contaminants
oto clean"
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filtration HEPA
photocatalytique
lampe germicide
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charbon actif groupe moto-ventilateur
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Wave number (cm"1)
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Diode
anode
cathode
n-Si/p-Si
n-GaAs/p-GaAs (InP)
n-CdS/p-CdTe
n-CdS/p-CulnSe2
Tistc = 15-50%
TCO: Al/ZnO F/Sn02 Sn/ln203
Substrat de verre
Conversion efficiency under stc = standard test condition
nstc =
PeitW/m2)
recu^tc
(1kW/m2)
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Characterisation of solar cells
Dark
V
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sun at zonith
sun at angle n to zenith
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Pin = 1 kW / m2
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Chromophore organique
1
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TI02 ou ZnO
Pr. Gerischer et al (Berlin 1960-1970)
< 1%
Rayonnement solaire dissipe par I'antenne solaire
~100%	
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Principe de construction des cellules photo-sensibilisees avec regeneration ionique
anode
ZnO ouTiO
12% (1987)
5% (1995)
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8% (1987)
cathode
Perovskite (D CHoNHoPbl,
L'analyse cinetique de la cellule photo-sensibilisee
BC_
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reaction du chromophore avec les ions d'iodure
transfert d'electrons a travers des agregats de Ti02
recombinaison interfaciale
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TWO-STEP (
4
1. Difference between « nano versus macro » in semiconductor photocatalysis.
2. How many elementary charges are needed to transform :
a) water into hydrogen and oxygen
b) C02 into CH4?
3. What are the essential radical states formed in photoexcited titania? Which applications are related to this process?
4. How function classical macroscopic and modern nanoscaled solar cells?
5. Give ay least three solar antennas used in nanoscale photovoltaics.
JMf "
L. Spanhel
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