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BEP structure prvsk solar cell - Coggle Diagram
BEP structure prvsk solar cell
Theoretical info
Solar cells
Needed properties
Micro properties
High carrier mobility
Strong absorbance
Long carrier lifetime (slow rec)
Efficient charge seperation
Junction
Homo = elec pot
Hetero = charge trans
Small exciton binding energy < KbT
Macro properties
High Jsc
High FF
High Voc
Are tested with an IV curve
Kintetic model charge carriers
States
Density of states
Density of certain energy levels
Trap states: Nt
At low exciton conc the trap states will be filled up first and determine recombination
At high exciton concentraties, trap density is to little and k2 will determine recombination
Only deep traps, electrons in shallow traps can still interact with phonons to get excited to the CB again.
Higher concentrations lead to faster processes
Charge carriers(conc)
nt
nh
ne
p0
dark carriers
Thermal equilibrium charges
Preferably are as low as possible
Rate constants/dynamic processes
Recombination
non-radiative recombination
Kd
From trap to vb
Kt
From CB to trap
energy released in the form of phonon generation/interaction
Is promoted when trap states are above vb maximum
At the interface(1ns-mis)
Interfacial recombination
ke for HTM
kh for ETM
k2
Second order recombination
ne*nh
Thus always will play a role at high enough charge densities
radiative recombination van CB to VB
Excitation
Gc = time depenent photogeneration
Direct dissociation
10^14/Cm3 in normal operating sc
Accumulation(1s)
Ion migration
Causes the hysterisis
Extraction (100<ps)
Holes
Kh
Electrons
Ke
Used to determine extraction yield
Charge diffusion to inteface (1ps-1ns)
Collection of charges at the opposing electrode
Effect higher T
Hightens recombination rate constants
Limitations
I Seggragations
reuse of fotons
Homogeneous in space
Electronic theory (per)
Bruillion zones
Semi-continious energybands consisting out of MO's from the bonding
Between the Bz are the forbidden regions: No MO's
CB/VB
k-space
In 3d crystal do the bond distances differ
K versus E diagrams are needed
Energies are also directional
Same k = direct bandgap
Different K = change in momentum needed = Less aborbtion/rec
Charge carrier mobiltiy
Lowered by
Increased phonon scattering
Because of acoustic phonons
Is lower at higher T with T^-1.3- -1.7
Polycrystallinity/grainboundaries/interfaces
Ionized impurity scattering
Because of charged defects
T^1,5/N, N = charged defects
Trap states
No close lying energy states = no mobility
Differs for holes and electrons
Search literature for mobilities
Can be helpfull to explain TRMC results
Handy if they are the same: no charge buildup of one of them
Can be seen as the speed of the charge carrier moving trough the material
Depends on
Time between scattering events
1/Relative mass electron/hole
Charge carrier diffussion length
R = root(D*t1/2)
Is highest for electron in trap states
Diffusion coefficient = dependent on mobility and effective mass electron
Ld = root(KbT*Mut/e)
Voc
Losses
Namely because of the defects/ non radiative recombination at the interfaces
Voc depends on inverted saturation current density Jo (rec), High recombination resistance lower J0 and increases Voc
Relatively low in bulk
Bad energy allignment
Until now the main focus point
Jsc
Almost maximum by sufficient charge separation/extraction
Phonons
Acoustic
Optical
Polarons
Quasi particle that can be associated with vibrating lattice atoms
FF
Can be seen of the ease of charge transport in the film to the electrodes
Has the best growth potential in prk psc's
Limiting factors
Radiative recombination
Inevitable and sets the theoretical upper limit of the FF on 90% according to the Shockley quesser model.
Non-radiative recombination
If the ideality factor and Voc is known, the SQ model limits the FF at 85%. Low ni and high Voc = high FF if no charge extraction losses. (green FF approximation)
Innefficient charge extraction
Most of the time results in FF below 70-80%
HTL is most of the time the cause for this
Low hole mobility
Make thinner layer for shorter carrier arrival at the electrodes (8 nm)
Long charge extraction makes 2nd order rec more prominent = more losses
Insufficient energy allignment
Especially for higher sun intensities
Ideality factor n
n = 2/a
a = the order of recombination
To describe the ideality of the recombination
n = 1 = ideal, rec limited by minority carrier
n = 2 = nonideal, rec limited by both carrier types
Charge separation
Thus excitons that result in free charges
Depends on temperature, Eb (5meV) and charge density
Is almost 1 if charge density stays below 10^16 cm3
Interfaces
Examples
PRK/HTL
PRK/ETL
Grain boundaries
Charesteristics
Causes many trap states
Interface recombination is the most prominent problem that has to be solved
High defect density by lattice mismatch
Carrier transport barrier
Causes band band bending
Interface engineering
Interface modification layers
Energy level allignment
Results in
Good carrier extraction
High FF
High Jsc
High Voc
Between prk VBM/CBM and CTL
Optimal dE = 0.2 eV
Still high enough driving force
No peak potential that hinders extraction
Measure the energy (WF) of the material first with XPS
Carrier dynamics
Recombination
Controls voltage
Passivate surface defects
Accumulation
Controls hysterisis
Extraction
Controls current
Trap passivation
Enhanced electronic coupling and chemical bonding can lower the amount of trap states
2d prk or functional molecules
Perovskites
Composition ABX3
1 monovalent cation (A)
Formamidinium (t=1)
Cesium (t=0.8)
Methylammonium (t=0.9)
Rubidium
1 divalent metal (B)
Tin
Lead
Germanium
3 Halides (X)
Iodide
Bromide
Chloride
Effect of composition
Determines structure, performance, stability
Bandgap
Energy difference HOMO-LUMO, are altered differently by composition change. More, less stable. Homo = b-s, x-p orbitals. Lumo = nonbonding b-p, x-p
Smaller used cations/halides results in a higher bandgap
Halide: Cl<Br<I
Larger halide gives bond more covalance caracter, less electrostatic
Cation: Ru<Cs<MA<FA
Larger cation stretches the metal-halide bond more
Energy levels do not contribute
Also alters the bondangle
Bandgap tuning happens often with different Br/I ratio
Stability
MA alone is thermally instable and should partly be replaced by Cs/FA for better stability
More different cations reduce chance phase seggragation Br/I
Both Sn and Ge are susceptible for oxidation to the unwanted 4+ state
Black phase
A tolerance factor of 0.9 gives best chance of black phase (0.8-1)
MA therefore gives best chance on black phase
Cesium and FA have to be combined to obtain the black phase, otherwise the yellow phase may form.
But more FA, because this favours the formation of the cubic structure (0.9-1.0)
Inorganic framework mostly determines electrical properties
Safety: Lead can dissolve, change with Tin/germanium is safer
More complex prk often have better perfomance
Thermally stable
Active fase
Less segragation
Effect more CS
Blueward shift + higher absorbtion
Higher exciton binding energy
More thermal stability
Less charge buildup on surface
Lower recombination resistance
Should be less than 0.3 for the structure
Alternative composition: A2BB'X6
Are used to avoid lead use
Still have low performance
Halide double perovskites
1 monovalent metal
1 trivalent metal
Properties
General
Positive
High electron carrier mobility
Long carrier diffusion length
Low defect density (especially for wet chemistry)
Low Eb
Negative
Rather unstable
current voltage hysterisis
Low reproducibility
Hard to make on large scale
Opto-electronic
Bandgap
Tuning.
With tuning mixed perovskites I-Br
1.58 eV for Cs0.1FA0.9PbI2.9Br0.1 (scvd)
Mix direct/inderect bandgap
Is a direct bandgap because of its high absorbtion
Is a inderect bandgap because of the temperature dependence of the recombination
Charge seperation
Exciton is formed after light absorption (electron hole pair)
Exciton binding energy is way lower than KbT for ordinary perovskite
Exciton thus easaly breaks up
Thin prk layer enables instant electron/hole take up bij etl/htl
Effect substrate
Has more effect on thinner prk films
Differs for different substrate with other interface dipoles
Can bend the the electronic structure and position of the VB and CB of the perovskite near the interface
Upward bending near interface makes charge exchange more difficult.
Charge carrier mobility
Dictated by inorganic framework
Less influenced by chose of cation
High enough to make diffussion not the limiting factor for charge extraction
Structure
Crystallographic
Phases
a-phase
Photo-active
Cubic structure
Black
d-phase
Yellow
Inactive
Hexagonal/orthorombic
Grains/Crystallites
100-1000 nm
Small internal columnar crystalline crystal
Bonding differnt orientatied crystallites = grain boundaries
Bigger grains +- = better film
Defects
Crystal defects
Phase seggragation
Accumulation iodide after illuminiation in mixed halide prk (verena)
Works as charge carrier sink
More unwanted recombination
Iodide domains have lower bandgap
Mechanisms
Photodegradation
Self doping tin
Add SnF2 for prevention
Self doping Ge
Thermal degradation
Chemical degradation
Point defects
Interstituals
These lead/iodide defects will produce deep traps
Anti-site substitution
Vacencies
Most studied defects prk
Interfaces
Grain boundaries
Ion migration
Enabled by ion vacencies
Cause of hysterisis
Moisture ingress
Main starting point for degradation
Must be passivated for long stable pvc
Reduces mobility
Surface defects
Undercoordination
Cation vacencies
Leads to unwanted non-radiative recombination(trap states)/deterioration
Countermeasures
Passivate grain boundaries
Antisolvent engineering
Use antisolvent with organic molecules that passivates grains
Hydrofobic crosslinking agent
Immobilises ions
Prevents water ingress
Bond with Pb in grain boundaries and on surface
Little excess PbI2
Will sit partly in the GB
Passivate surface defects
Use organic layer (TBA+) to fill up vacencies, to smoothen surface
Passivate the undercoordinated ions in some way
Annealing
Less grain boundaries
Doping/substitution
Adding material for enhanced crystallisation, larger grains
CspbI3
Limits distribution GB
Also limits ion migration
Guanine
Enables stable quartanary structure
K
Retards nucleation
Relation with trap density
Common trap density's
10^14/16 for MaPbI
Same order as the excitation density
Common defect density
Only certain defects lead to trapping intraband states
Below 10^14 should not be a problem
Perovskite-Si tandem
Has the problem that no conformal layers can be formed on textured silicon
scvd is ideal in that case
Charge transport layers
HTL
Commonly used
P-I-N conf
Organic
Spiro
TTB
Has even without doping a good hole mobility
Is very hydrofobic
Good energy allignment
TAD
MeOTad
The extra O makes it less hydrofobic
Small organic molecules
Are easy tunable
MeOTTVT
Low cost
Inorganic
N-I-P conf
Inorganic
Organic
Spiro
OMeTa
To expensive
Has to be doped
Performs well
Needed properties
Great hole mobility
Bandgap allignment
Energy is 0.2 eV higher than the VBM
Hole selective
Full surface covarage
Hydrofobic
May not dissolve in prk precursor solution
Dopants
Used
Tbp
Can reduce stability by ion migration
Are added to enhance hole mobility
Only for solution based HTLs
p-type semiconductor and kh >>ke
ETL
Needed properties
Bandgap allignment
Energy is 0.2 eV lower than the CBM
Electron selective
Good electron mobility
Full surface covarage
Against current leakage
Commonly used
N-I-P
Tin oxide
Low temp dep
Favourite
Zink oxide
P-I-N
PCMB
Are fullerene derivatives
Lower hole mobility
Better solubility
Expensive
Fullerene c60/c70
Use their mixture for better solubility
Can go in grains to passivate (solution based)
Shows no hysterysis
Can function up to 1 nm
Affects
Morphology
Interface
Responsible for recombination
Trap states
Recombination
Energy level
Carrier collection
Electron mobility
Charge transport/collection
Is a n-type semiconductor and ke >> kh
General
Needed properties
Electronic
High hole/electron mobility
Good energy allignment
Selective
Easy tunable
May not induce extra trap states/ hysterysis
Low cost
Stable
Also with prk annealing
Dopant free
Easyer for large scale production
More stable
Thin
May not generate current --> very large bandgap
Hydrofobic
For structure and to deflect moisture
Good solubility if solution based
Function
Because electrodes are not selective
Voc losses
Selectively capture holes/electrons
CTL have to be compatible with absorbing layer and type of configuration. Other conf often use other CTLs.
Connects the perovskite with the electrode
Make trap states less of an issue by its short timescale
Are semiconductors
Properties
Have mobility << 1
Material/methods
Analytical methods
Focus points
Structure
Crystallisation
Morphology
Crystal structure
Photoelectrical properties
Hole/electron injection effciency
Defect density
Charge carrier liftetime
Apparatus
Time-resolved microwave conductivity (TRMC)
Theory
Wavelengths used
Use of photon +- 100-200 nm below bandgap = full absorption and still decent homogeneous penetration in the film to have uniform charge carrier formation.
Visible/infrared laser light + microwaves 8-12 GHz
Use microwaves with the most absorbtion or that produce the standing waves
Both are monochromatic
Thick samples > 500 nm even need way less
Interaction with microwaves
Some of the incident microwaves get absorbed by the mobile charge carriers. The rest is reflected back
The percentage of absorbed mw is a measure for the conductivity --> KdG
8.2 - 12 GHZ
Using a holder with an cavity introduces resonance and higtens K. An open cell needs therefore higher intensities of light. But has a better response time
K depends on
Wavelength used
Medium used
Container used
Effect laser
Photoexcites excitons(creates mobile charge carriers)
Increases the conductance dG of the film
4 ns laser
Obtained results
Processing
Is the avarage of 10-1000 laser pulses
Is the convolution of the real n*m and the response time function
response time is when the response reaches 1-1/e
response function is a exponential like function
Can be normalized to the number of photons absorbed with I0/FA
Implications
Low charge densities get more affected by trap states
Long tails
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Use to determine trap density
Use a kinetic model to extract quantative data
Credibility
Only accurate if dmV is below 200
Determine the temperature of the sample!!!!!
If Eb is low it is assumed that every photon creates 2 cc --> phi is 1
Phi = fraction of absorbed photons leading that lead to the generation of free charges.
Conductivity
e*N(me+mh)
avg mobilities holes and elec
Number of cc
Increases at lower temperatures
Conductance sample
Conductivity
Structure factor b
Length
Doesnt has interface effects like elektrodes
Used sample holder
Ellips cell
More sensitive, k = 70000
Lower intensity needed
Has a time delay, cannot measure quick events
Standing mw first has to be measured
Open cell
Higher intensity needed
Damages the sample easier
Less sensitive, K = 1000
Only lets 80% light pass through grating
Knoop in je oren dat een lange rechte lijn goed is, je wilt alleen geen lange gehalveerde staart.
Effect charge transport layer
The mobility reduces to only the electron/hole contribution
It can create more traps states
Charge extraction is almost intantanious and cannot be seen <3 ns
Measure the front/back to see if the diffussion length suffices
The CC in the TM are almost not seen because of their low mobility
Causes lifetime extention for the remaining charge carrier
The absorbtion of C60 causes less light absorption
Graph
y-as = Normalized conductivity
x-axis = time after laser pulse (100 ns = short, 1Mis = long))
Sharpness/noise graph is altered by using different light power, sensitivity oscilloscope
Used for
The opto-electronical properties of the prk film
Charge carrier mobility
Type of recombination and their rate
Charge carrier lifetime
Defect density (number of trap states)
To measure the change in conductivity(free charge carriers) of a semiconductor with a low background conductivity
Method
Preparation
Turn on laser 30 min for measurments
Let the laser reach > 30 C
Prepare the samples
Mount the sample in the holder (prk towards short side)
Turn on the 3 verlengsnoeren
Measure the maximum power at Lambda
Use power meter
Take the mean value
Alter the range to sensitive
Write down in notebook/computer
Use a frequency scan to measure best Mw
Measurements
Write down all relevant parameters
MNumber/Sname
Exciton density per Cm^2
Avarage traces/waves
Sensitivity/timescale
Max power laser
Start to measure at different intensities starting from below by applying different filters (never 2 and 3)
Set sensitivity(5, 10, 20, 50 meV) and timescale and check response
The higher the light intensity, the lower the percentual intensity difference with the next measurement
Measure the eclips cell first.
Safety
Laserlight can also be invisible
Watch out for reflections
Press interlock to stop laser
Different wavelength come out of laser
Result handling
Macros to obtain plot
Append other measurements to the same plot
Make a legend
Measure with UV-VIs the absorption to compensate the graps
Use Commands to make graphs all alike
Components
Sample
Circulator
Separates incident en reflected mw
Voltage controlled oscillator
Microwave detector
Pulsed 4 ns Laser
Storage
Light filters
XRD
Used for
Indicates when unwanted structures are formed
Shows the crystallinity of the sample
To confirm the quality of the sample
Theory
Light is diffracted according to braggs law
Has to suffice this relation
If lambda is in the order of d
For contructive interference
n*lambda = 2 d sin(theta)
lamba = wavelength photon = constant
n = 1
d= distance between scattering planes
Usings larger atoms results in higher d
If a is known, d can be directed to the corresponding plane (miller indeces)
Sample can rotate to account for the multicrystallinity
Peak intensity
Only planes that are perpindicular to the normal of the surface are visible in the diffraction diagram
Thickness sample
Illumination time/area
Intensity x-ray beam
Structure factor
Surface roughness
Only the ratio of peak intensity can be used
X-rays creation
Accelerated electrons knock out low lying electrons in Cu orbitals
3 x-ray wavelengths are emitted corresponding to different electron fallbacks
Therefore crystalline samples show double peaks
Crystal size determination
Only works if crystallites are nano-size
L = (K
lamda)/(peak broadening
cos(th))
Graph
How higher(relative)/smaller the peak the higher the long range order --> larger crystallites
Broad low signals indicate an amorphous phase
Sometimes peaks of the substrate show when the film is thin
Crystalline prk can show peaks of (001), (002) and (003) planes if perpendicular to the normal of the surface
Method
Place in XRD machine alligned with laser
Indicate scan type(coupled twothetha), range, step size, step time, voltage/current, illuminated area
Level the top of the film and make sure to level the heigt with that of the container.
Use chemical filter or database to assign the measured peaks
Tune the roosterconste to get good allignment
Miscellaneous
PbI2 can form sheet like structures
Normal c = 6.8 a
Shifted c = 13.6 a
uv-vis spectroscopy
Determines
Transmission
Absorption
Reflection
PRK has 20% reflection
Reflection is less when Glass is in front
To determine bandgap, TRMC wavelength and FA for correction
Method
Set range, slit width and absorption/reflection
Do an autozero for every different measurent
Align the laser for the first time
Take the right sampleholder and do the measurement
Start the lamp and thereafter the software
Export the data and turn of the software/lamp
Components
Sphere
Middle position
The transmission and reflection is measured
Back position
Only the reflection can be measured
Front opening
Only the transmission can be measured
Detector
In the middle of the sphere
Is white to reflect all the light to the detector
SEM
Structure
Layer thickness
TRPL
Less suited for re-absorbance or non-rad rec materials
Only detects radiative recombination
So does not tell much about the dynamics
xps
Knocks electrons out of bands with x-rays
Can determine the electronic band structure
Determines the work function (ion energy)
Needed for energy alignment with CTLs
Profilometer
Measures the thickness of your samples
Method
Make two horizontal scratches in your sample
Samples thickness is measured between the scratches
Average height is measured
Transient absorption
Kon volgens Tom ook nog handig zijn om te meten
Making perovskite film
Application on substrate
Non-solution based
Sequential chemical vapor disposition
Advantages
Exact thickness control
No solvent needed
Are often toxic
Possible on rough substrate
Gives smooth surface
Gives lower defficincy by scale up
Easyier to measure than co-evaporation
Method
3 sources
Cesiumbromide
Formadiumiodide
Lead(iodide)2
250 nm CsxFA1-xPbI3-xBrx film
Deze haalde 16%
The 3 sources are subsequently heated at different temperatures and deposit their contence one at the time
The temperature controls the deposition rate
Disadvantage
Hard to reach perfect stoich
Complex machinery needed
CO-evaporation
Deposition ''mechanism''
Effect substrate on structure
Difference in segregation/grain size/composition
Substrate has an effect on the convertence of pbi2 to perovskite
Controls the columnar grain growth
Because of the preffered plane that binds to ther surface
Substrate can decompose MAI that hinders formation/sticking up to 30 nm
Nucleation
Nucleation is slow
Many nucleation points
Grain
Orientation
Can be measured with xrd
Growth
Has an preferred growth plane 111
Grows sideways if 100 bind to surface
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Grows straight if 111 binds to surface
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Ostwald ripening
3 more items...
Smaller than solution based
Process parameters
Temperature
Towards sublimation temp
Surface properties substrate
Evaporation rate
MAI has low collision length = CVD (Concentration dependent)
Can be tuned for optimal stoich
PbI2 has high 20 cm mean free path (effusive)
Happens in vacuum
Difficulties
Difficult to measure amount evaporated
Low evap enthalpy
High volatile organic MAI
Substrate
Best
Is non-polar
Organic substrates
1 more item...
Has nice columnar grains
Worst
Polar
Titatinium oxide
Solution based
Blade coating
Disadvantage
High speed gives lower quality films (add surfactant)
Method
A perovskite solution is made and released from a blade that moves over the substrate at a certain height and velocity.
Advantage
Relatively quick (180 m/ h)
Can deposit large films > 10 cm^2
Spin coating
Disadvantage
Only for small surfaces
Uneven thickness by spinning
Hard to control thickness
(Anti)solvent may dissolve TPs
1st used method
Full prk solution is deposited on substrate and spon.
Then the anti-solution(dissolves only the solvent) is added and spon to remove the solution from the film
Anti-solution can mess up when added unadequatly, but hard to not use it.
Rapid nucleation and crystallisation occurs
The samples are placed on top of the hot plate for some time
Advantage
Gave best efficiency PSC's
Low equipment cost
Types
One-step
Parameters
Concentration precursors
Annaeling temperature/time
(anti) Solvent (ratio/amount)
Acceleration, rotation speed
Spin coat time
Moment of dropping AS
Thickness control
RPM
Time in ozon cleaner
1 more item...
Concentration
Polarity surface
Two-step
Dynamic
First CsPbI is spin coated
FA/MAI is added during rotation
Higher PCE and smoother surface
Static
First cspbI is spin coated
FA/MAI is added without rotating
Gives larger grains, less PbI residue
Ostwald ripening and ion exchange happen together
Mixed crystal orientation will form
Used solvents
DMF
IPA
DMSO
Used antisolvents
Chlorobenzene
Ethyl acetate
Thickness control
Are utilized the most for there easy use
Inkjet printing
Spray coating
Slot-die coating
Focus points
Scalability
Want to have easy scalable processes for commercialisation
Larger areas generally give lower quality films
Less uniformity
Higher serie resistance
Some methods have limits in max film area
Cost
Deposition in ambient conditions is cheaper
Important factor for chose of method
Precursor solution may not dissolve deposited CTLs
Change the used solvent if so
Quality assurance
Pollution
Substrate has to be clean
Substrate can be cleaned with ozon machine
Substrate can be cleaned with ultrasonic bath
Degradation
Prk degrades in contact with O2 and moisture
Work under N2 conditions in compartment
Prevent re-exposure to hot T
Recognizibility
Mark the bottom of the used substrate
Safety
Lead is highly toxic
Annealing (after treatment)
Increase in grain size
Most of the time results in higher efficiencies
For example heating to 310 C and thereafter rapid cooling to enlarge grains and enable black phase formation.
Vapourizes solvent
Making a PSC stack
Cathode
ITO
ETL
C60
PRK
Anode
FTA
ITO
HTL
Spiro-ttb
PTAA
Glass
Configuration
Planar
Inverted p-i-n
Light shines trough HTL
Advantage
Compatible with tandem si cell
Contains less corrosive material
Organic ETM has better electron mobility
Regular n-i-p
Advantage
Overall higher Voc
Light shines trough ETL
Without CTLs
Easier to make
Still low performance
Mesopourous
Harder to make
Transport layers
Often organic/inorganic combination
Metal oxide is used as bottom tp, because thermal resistant (titanium oxide)
Two organic transport layer system is hard to achieve due to thermal degradation by the perovskite annealing.
Organic is used because of better transport properties
Warning: ik heb papers die wat anders stellen, die wel c60 en spiro samen gebruiken
Deposition CTL
HTL
Thermal evaporation
Spiro-ttb
30 nm
Spin coating
Spiro-OMeTAD
100 nm
ETL
Thermal evaporation
C60
20 nm
General
Deposition types
Spin coating
Thermal evaporation
Thickness
20 nm for C60
And full surface covarage
Thin layer is preffered
But Ag cathode may not penetrate (30 nm)
Method
Close the lit and reach vacuum (10E-7 mbar)
Let the evaporation reach steady state
Tape the sample to the holder
Transport the sample in container to the evaporater
Put the rotator on the lit (15 rpm)
Deposit the required thichness
No dopants possible
Use a thin layer
Preferred
Low temperature deposition
Without solvent
Quality layer without extra traps by poor interface
Without dopants
Research
Old research problem
Context/relevance
Good quality perovskite layer is needed
Perovskite sc are cheap+high eff
Options for silicon tandem cells
Problems
Cs-based material seggragation
non-conformal layer deposition on textured substrate
Goal
Effect substrate type and morphology(shape) on prk film properties
Substrate types
Flat silicon wafer
Monocrystalline semiconductor
Textured silicon wafer
Flat quartz
All coated/uncoated with Spiro-TTB
Has propably better surface properties
Is an organic hole transport material
Let op, het gaat dus meer over de ondergrond(substrate) dan echt over de verhouding van de componenten van pvk.
Substrate like in monolithic tandem solar cells
Supervisors
Jin
WIll help me with the evaporation
Jiashang
Will help me with the TRMC measurements
Old search queries
Triple cation perovskites
Interfaces
Interface defects
Interface induced recombination
n-i-p perovskite
effect substrate Interface
Spin coating
Nucleation and crystallisation model spin coating
PSC stack
C60
HTM
Spiro-TTB
ETM
Electrodes perovskite
TRMC
Failed, nothing found
New research problem
Goal
Test the effect of C60 en Spiro-ttb/Spiro-OMeTAD on the opto-electronic properties of the stack using TRMC, xrd and uv-vis
Using an inverted p-i-n structure
Using the hybrid method
CTLs are evaporated
Perovskite layer is spin-coated
Never done on this type of perovskite with TRMC
Variable could be changing the bandgap with using more Bromide
Possible different samples
Substrate-spiro-prk
Substrate-prk-c60
Substrate-prk
Substrate-spiro-prk-c60
Substrate-c60-prk
Substrate-prk-spiro
Probably a few samples each
Substrate-spiro
Substrate C60
On the planning so far
3 Substrate-Spiro-PrK C60
p-i-n under iAM1.5 llumination
Made samples
Spin coat prk Batch 1
30 s
4
XRD
Damaged
Used for the profilometer
2
Unused
5
Used for uv-vis
Broken in two pieces
1
Unused
Made by Jiashang
Shows some physical damage
6
TRMC --> Spiro --> TRMC
7
TRMC --> C60 --> TRMC
Found again
3
TRMC --> spiroometad-->TRMC
25 s
9
TRMC -->spiroometald-->TRMC
10
TRMC --> spiro --> TRMC
8
XRD --> uv-vis (10/05)
Damaged
What still can be done
3 spiro-ometad - prk - C60 samples
C60 bottom batch 1 + prk batch 2 + spiro-ometad batch 1/2
2
With prk
spiro-OMeTAD batch 2
3
With prk
Looks fairly damaged
spiro-OMeTAD batch 1
Gave best lifetime
1
With prk
Best looking
spiro-OMeTAD batch 2 (CB)
4
Used for uv-vis
Without prk
Again with uv-vis with annealing 135 C for 20 min
Turned mustard yellow
PRK ref 1
Spiro-TTB bottom batch 1
2
3
1
4
Used for uv-vis
Did not correlate with literature spiro.
Not used
Spiro-OMeTAD bottom batch 1 (DCB) + prk batch 3
2
With prk
+c60
3
With prk
+c60
1
With prk
c60
4
Used for uv-vis with and without annealing
Slight change absorption spectra
Deposited perovskites have some holes, imperfections
PRK ref
2
1
Dropped AS after 35 s, unused
Probably added to much MABr, due to weighing problems
Results
Trilayer
Extraction is hindered at higher intensities
Intensity dependence differs greatly between configurations
Bilayers
C60 affected by position
Annealing
Substrate dependence
Spiro-OMeTAD unaffected by position
General
Extraction is limited at high intensities
Seen extraction can take >>1 ns
Holes/electrons have similar mobilities
Research branches literature
Understanding physical behaviour prk
Passivation of defects
Deposition methods
Question list
Do electrons have to be in one position to fall in a trap?
Can we add the alumuminum passivating layer + CTL?
Presentation
Notes
Add the layers to every slide
Add where the light is coming from
Less graphs in presentation
If the graps look the same, why show them all?
TRMC spiro is the same everywhere: top and bottom
It is logical that every graph seems the same at high intensities: 2nd order recombination and extraction cannot keep up.
New search queries
Internal electric field
band bending
charge effect transport layer
Extraction
rate
percentage
Back rate
Dependence on intensity
diffusion charge carrier in electric field
Saturation transport layer
Mobility
Thickness
Energy leves
Substrate dependence interface
Everything with TRMC + transport layer