UNIVERSITÀ DEGLI STUDI DI LECCE
Corso di laurea in Ingegneria dei Materiali
A.A. 2001/2002
Scienza e Tecnologia dei Materiali Ceramici
SELF-CLEANING GLASS
and
ELECTROCHROMIC GLASS
Professore
Studente
Dott. Antonio Licciulli
Daniela Lisi
SELF-CLEANING
GLASS
SUMMARY
HISTORY
TITANIUM DIOXIDE
SELF-CLEANING SURFACE
PHOTOCATALYSIS
HYDROPHILICITY
SUPER-HYDROPHILICITY
SELF-CLEANING WINDOWS
HISTORY
The late 1960s: the University of Tokyo research
photoelettrochemical solar cells. The solid-state
photovoltaic device has become the technology of
choice.
1972:
Fujishima and Honda discovered the
photocatalytic splitting of water on TiO2 electrodes
without using electricity.
1977:
Professor Allen J. Bard and co-workers at the
University of Texas first examined the possibilities of
using TiO2 to decompose cyanide in water. Many
important fundamental results concerning TiO2
photocatalytic reaction have been clarified by such
intensive works.
The late 1990s: Pilkington, PPG, SSG patent SELF-CLEANING
windows.
TITANIUM DIOXIDE
PHOTOCATALYST
HYDROPHILIC
SELF- CLEANING and
ANTIFOGGING functions
TITANIUM DIOXIDE
ANATASE
RUTILE
Density:
4,2 g/cc
2,76
Refractive Index: 2,52
TITANIUM DIOXIDE
TITANIUM DIOXIDE
White pigment in paints, cosmetics and foodstuffs.
Semiconductor transparent in the visible region of the
spectrum.
Low costs material.
Chemically inert, non-toxic, biocompatible.
SELF-CLEANING SURFACE
TO CLEAN SURFACE OF BUILDING
MATERIALS CAUSES:
Considerable trouble.
High consumption of energy.
Chemical detergents.
High costs
SELF-CLEANING SURFACE
TO REALIZE SELF-CLEANING MATERIAL SURFACES
THERE ARE THREE PRINCIPAL WAYS :
Super-hydrophobicity.
Photocatalysis.
Super-hydrophilicity and hydrophilicity
HYDROPHOBICITY
Hydrophobic materials ("water hating") have little or
no tendency to adsorb water and water tends to
"bead" on their surfaces (i.e., discrete droplets).
Hydrophobic materials possess low surface tension
values and lack active groups in their surface
chemistry for formation of "hydrogen-bonds" with
water.
HYDROPHOBICITY
CONTACT ANGLE
For a given droplet on a solid surface: the contact
angle is a measurement of the angle formed
between the surface of a solid and the line tangent
to the droplet radius from the point of contact with
the solid.
HYDROPHOBICITY
SUPER-HYDROPHOBICITY
The LOTUS EFFECT
PHOTOCATALYSIS
WHAT IS IT?
The acceleration of the rate of a
photoreaction by the presence of a
catalyst (semiconductor particle).
PHOTOCATALYSIS
WHAT IS a SEMICONDUCTOR SOLID?
PHOTOCATALYSIS
HOW DOES PHOTOCATALYTIC
SEMICONDUCTOR WORK?
TiO2 AS PHOTOCATALYST
TiO2  h   h  e
D  h  D 
H2O  h   OH  H
A  e  A
O2  e   O



2
TiO2 AS PHOTOCATALYST
OXIDATION-REDUCTION REACTION
ON THE SURFACE OF TIO2
TiO2 AS PHOTOCATALYST
IT IS COMPETITIVE BECAUSE:
A low-cost material is used as photocatalyst.
The reaction is quite fast at mild operating conditions
(room temperature, atmospheric pressure).
A wide spectrum of organic contaminants can be
converted to water and CO2.
No chemical reactants must be used and no side
reactions are produced.
TiO2 AS PHOTOCATALYST
PRACTICAL APPLICATIONS
HYDROPHILICITY
Also called hydrophilic, is a characteristic of
materials exhibiting an affinity for water.
Hydrophilic literally means "water-loving" and
such materials readily adsorb water. The
surface chemistry allows these materials to
be wetted forming a water film or coating on
their surface.
HYDROPHILICTY
HYDROPHILICTY
MECHANISM OF PHOTO-INDUCED HYDROPHILICITY
HYDROPHILICTY
TIME DIPENDENCE OF
THE WATER CONTACT
ANGLE IN AMBIENT
ATMOSPHERE
a) Upon UV illumination
b) In the dark
SUPER-HYDROPHILICITY
SUPER-HYDROPHILICITY
SCHEMATIC DIAGRAM OF
SUPER-HYDROPHILICITY MECHANISM
STEP 4
1
2
3
SELF-CLEANING WINDOWS
SELF-CLEANING WINDOWS
SunClean Glass
SELF-CLEANING WINDOWS
SunClean Glass
SELF-CLEANING WINDOWS
Pilkington Activ™
SELF-CLEANING WINDOWS
SGG AQUACLEAN
ELECTROCHROMIC
GLASS
SUMMARY
OPTICAL SWITCHING TECHNOLOGY
SMART WINDOWS
THE SOLUTION SageGlass®
OPTICAL SWITCHING TECHNOLOGY
It changes the view of glazing from a FIXED
element to a DYNAMIC one.
OPTICAL SWITCHING TECHNOLOGY
Optical switching materials can be used for
windows where optical and thermal
modulation is required.
OPTICAL SWITCHING TECHNOLOGY
THE PURPOSE IS:
to control the flow of light and heat into and
out of window, according to an energy
management scheme.
OPTICAL SWITCHING TECHNOLOGY
THE BASIC PROPERTY IS:
a large change in optical properties upon a change
in either light intensity, spectral composition, heat,
electrical field, or injected charge.
OPTICAL SWITCHING TECHNOLOGY
This
optical
change
results
in
a
transformation from highly transmitting state
to a partly reflecting or absorbing state, either
totally or partly over the solar spectrum.
SMART WINDOWS
Electrochromic windows change the light
transmittance, transparency, or shading of
windows in response to an environmental signal.
SMART WINDOWS
HOW ECDs WORK?
SMART WINDOWS
HOW ECDs ARE MADE?
A voltage applied across the transparent conducting oxide layers
causes hydrogen or lithium anions (A+) to be injected into the
electrochromic layers.
SMART WINDOWS
ELECTROCHROMIC MATERIAL
PERFORMANCE OBJECTIVES ARE:
continuous range in solar and optical transmittance, reflectance,
and absorbance between bleached and coloured states;
contrast ratio (CR) of at least 5 a 1;
colouring and bleaching times (switching speed) of a few minutes;
switching with applied voltages of 1–5 V;
acceptable neutral colour;
large area with excellent optical clarity;
sustained performance over 20–30 yr;
acceptable cost ($100/m2);
SMART WINDOWS
GLASS/ITO/NiO/Inorganic Electrolyte/WO3/ITO/GLASS
WO (clear)  xe  xM  M WO (deep blue) (M  H, Li)
3
x
3
NiO (clear)  xOH  NiO(OH) (gray)  xex
SMART WINDOWS
GLASS/ITO/NiO/Inorganic Electrolyte/WO3/ITO/GLASS
SMART WINDOWS
GLASS/ITO/NiO/Inorganic Electrolyte/WO3/ITO/GLASS
SMART WINDOWS
GLASS/ITO/PANI/PB/PAMPS/WO3/ITO/GLASS
SMART WINDOWS
GLASS/ITO/PANI/PB/PAMPS/WO3/ITO/GLASS
SMART WINDOWS
ECDs as ENERGY SOURCE
SMART WINDOWS
ECDs as ENERGY SOURCE
THE SOLUTION
SageGlass®
THE SOLUTION - SageGlass®
THE SOLUTION - SageGlass®
THE SOLUTION - SageGlass®