Perovskite solar panels withstood 1800 hours heat stress

Australian
chemists have found
protective
coating can not only protect
perovskite
solar cell
from moisture, but increase it
heat
stability.
This
the coating helped the least stable
perovskite solar cells for the first time
pass international
certification IEC61215:2016,
in particular, they withstood heating to 85 degrees C for 1800 hours and several cycles of cooling to -40 degrees Celsius.
Results
research published
in the journal Science.

Efficiency
perovskite
solar cells
increased
from 3.8 to 25.2 percent of the total
in the ten years.
These solar cells are simple
in getting cheap and can
be used to convert solar
light in electricity
as
independently
and as top translucent
part of the tandem
solar
elements.

Main
the perovskite problem
materials
remains the lack of stability.
Under
sunlight, heat,
and oxygen and atmospheric moisture,
perovskite solar
elements
degraded —
them getting worse
charge extraction from the active layer on
electrodes
starts
migration of ions between
layers
and in the later stages
is the destruction of the crystal
the lattice of the perovskite.
Now
scientists are actively looking for ways to improve
the stability of such
solar
elements such as developing
for
them
various encapsulating coating
for
protection from oxygen and moisture.

Anita
Ho-Bailey (Anita
W. Y. Ho-Baillie) of
The University of New South Wales and
her colleagues informed
already suggested
simple
and effective
a method of encapsulating
perovskite solar cells with
using glass
and fast freezing
polymers.
In the new work they have perfected
this
method
and used
it
for
encapsulate the
unstable
perovskites

containing methylammonium group (MA).
Perovskite
items methylammonium show
the best efficiency but the worst
stability, especially sensitive
such materials to heat.
The authors
work have studied the stability of two
perovskite materials
Cs0.05FA0.8MA0.15Pb(I0.85Br0.15)3
and
FA0.85MA0.15Pb(I0.85Br0.15)3,
which
contain
15 mole percent methylammonium
cation. For
encapsulation used the usual
thin glass
which
“glued” to the solar element
with
fast freezing
polymer
materials
but
based
polyisobutylene
(PIB)
or
polyolefins
(PO).
The authors
tested two ways of applying
polymer — in
one case
were only on the edge of the solar
item
and
in the second case
for the rest of his
surface.

Most
reliable
turned out to be a full encapsulation with
a polyisobutylene.
All
samples
with
such encapsulation
showed
the stability level corresponding
international certification sun
elements IEC61215:2016,
it
have withstood 1000 hours of heating to 85
degrees Celsius, and 10 cycles
cooling to –
40
degrees Celsius, followed by heating
to 85 degrees Celsius. Both experiments
conducted at a relative humidity of
85 percent, and certificate
get the items that
in
the end of the test save
efficiency of at least 95 percent of
initial.

Solar cells based on
Cs0.05FA0.8MA0.15Pb(I0.85Br0.15)3
in
both experiments showed
even
better stability than you have — withstood
1800 heating hours and 75 cycles of cooling/heating.
Samples with full encapsulation
polyolefins
successfully
passed part
test cycle,
but
could not resist
test long
heat
stress
(the best
the sample lasted 564 hours).
But samples from the edge of the encapsulation
showed insufficient stability
in
both cases.
Note
what
perovskite
solar cells containing
matrimony successfully passed the certification
IEC61215:2016
for the first time
in history.

Curious
encapsulation, according to
apparently
not only increased the stability of the solar
elements the humidity, but
thermal stability.
The authors suggested that the following
explanation: when
the decomposition of perovskite material
it turns out a lot of gaseous products:
ammonia (NH3),
yodovidona (HI)
bromovalerate
(HBr),
methyl bromide
(CH3Br),
under the conditions of the
(CH3I),
methylamine
(CH3NH2)
and
hydrogen cyanide
(HCN).
When
this process of decomposition perovskite
is invertible, and, if
all the gaseous products securely
sealed
inside
after some time
the system is installed
balance. If the encapsulation
leaking
and gaseous
products leave
the system, according to the principle of
Le
Chatelier —
Brown,
balance constantly
shifting
in the direction of decomposition of the perovskite
material.
It
the assumption was
confirmed by the data
gas chromatography and
mass spectrometry.
When
heating control deencapsulation
samples were fixed allocation
ammonia, methylamine
other gaseous products,
and
when heated
encapsulated
samples

no.

This
way results
Australian chemists show
encapsulation can not only protect
perovskite solar cell from moisture
and oxygen, but also enhance its thermal
stability.
Proposed
method of encapsulation is cheap and simple
can be used for laboratory
samples and for perovskite solar
items received industrial
way.

Scientists
testing and other methods of stabilization
perovskite solar cells.
For example, German chemists showed,
that extra layer of tungsten oxide
can reduce the loss
current on the boundary between layers and slow
chemical degradation of the material.

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