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Organometal-halide Perovskite Solar Cell: High Efficiency, Up-scaling process and stability

Fabio Matteocci

CHOSE – Center for Hybrid and Organic Solar Energy

Department of Electronics Engineering

University of Rome «Tor Vergata» (Italy)

fabio.matteocci@uniroma2.it

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http://www.nrel.gov/ncpv/images/efficiency_chart.jpg

Best Single-Junction Solar Cells

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Perovskite: ABX3 structure

Phase Transition (CH3NH3PbI3): Orthorhombic Tetragonal Cubic 162 K 327 K (54 C) The organic ligand is disordered in Tetragonal and Cubic phase.

Nature. 2013, 12, 1087 J. Mater. Chem. A, 2013, 1, 15628

Applications • Superconductivity • Fuel cells • Piezoelectric • Sensors • Solar cells • LEDs • Lasers

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Panchromatic absorption & high absorption coefficient

Flexibility, transparency, low light workability

ambipolar charge-carrier

mobilities

long exciton lifetimes/diffusion

length

very low exciton binding energy

Up to 90% Absorption in Visible spectrum

Up to ~1 micron

How good are perovskite solar cells?

IPCE Fig Courtesy: H. S. Jung and N-G. Park, small, 2014

MAX3 can works as electron as well as hole transporter

Eperon, G. E., et al. (2014). ACS

Nano.

Hodes, G. (2013). Science 342, 317-318.

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Tunable Band Gap

CH3NH3PbI3-xBrx Perovskite

By the insertion of Br atoms (x) on the

perovskite cristalline structure, the energy

gap can be increased.

Noh, J. H., S. H. Im, et al. (2013). Nano Lett 13(4): 1764-1769.

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Monolithic Tandem PSC/c-Si

Conversion efficiency up to 20% on 1.5cm2

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PSC Device Architecture

ABX3 Perovskite

p i

n

Heo, J. H., S. H. Im, et al. (2013 Nature Photonics 7(6): 486-491.

Light

TiO2/CH3NH3PbI3 /HTM

Good hole and electron diffusion length (from

100 nm to 1 μm)

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Device: Mesostructured vs Planar B

oix

, P. P

., K. N

on

om

ura

, et a

l. (20

14

). "Cu

rren

t pro

gre

ss a

nd

futu

re p

ers

pe

ctiv

es fo

r

org

an

ic/in

org

anic

pe

rovskite

so

lar c

ells

." Ma

teria

ls T

od

ay 1

7(1

): 16-2

3.

Easier perovskite grown

Better charge collection

Easier perovskite grown

Better charge transport

Less production step

No sintering step

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Cross Section: Device Architectures

DSC-based Perovskite Solar

Cell:

c-TiO2 Thickness: 70nm

mp-TiO2 Thickness: 700nm

Single-step Perovskite with Cl

No Perovskite Overlayer over

the TiO2 film

HTM thickness: 200nm

Maximum PCE: 10.6%

c-TiO2 Thickness: 40nm

mp-TiO2 Thickness: 150nm

Double-step Perovskite

Perovskite Overlayer: 150nm

HTM thickness: 200nm

Maximum PCE: 18%

Optimized Perovskite Solar Cell:

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Solution Processing

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Solution Processing

Solution processing of transparent conductors: from flask to film, Chem. Soc. Rev., 2011,40,

5406-5441

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Several deposition methods

Spin coating perovskite Drying RT Annealing 90-130°C

1) One-step procedure

1a) 3 CH3NH3I + PbCl2 → CH3NH3PbI3-xClx + …

CH3NH3I + Pbl2 → CH3NH3PbI3 1b) Solvent engineering

Nam Joong Jeon et al. Nature 517,476 (2015)

PbI2 deposition CH3NH3I dipping

Perovskite layer

2) Two-step procedure

J. Burschka, et al. Nature, 2013, 499, 316

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Impact on the Perovskite morphology

Article in preparation

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Up-Scaling Process

10cm2

Up-scaling Issues:

Deposition Uniformity

Patterning Procedures

These issues have been studied to reduce:

• The PCE loss from small area to larger one

• The PCE loss from large area cells to the

module 100cm2

0.1cm2

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Module Fabrication

FTO Patterning Screenprinted Mask c-TiO2 Deposition

Mask Removal n-TiO2 Deposition Perovskite Deposition

P3HT Deposition Gold Evaporation Module

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Laser Patterning Procedures (LPP)

CO2 Laser

(l=10µm) Au deposition

Nd:YVO4 Laser

(l=532nm)

Au deposition

LPPPEROVSKITE

nc-TiO2

FTO

BL-TiO2

Perovskite

LPPP3HT

CO2

Laser P3HT

LPPPEROVSKITE/P3HT

nc-TiO2

FTO

BL-TiO2

Perovskite

P3HT

F. Matteocci et al. Prog. Photovoltaics (2014) DOI: 10.1002/pip.2557

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Optimization of the laser patterning

FF=78%

FF=55%

Module number Layer Patterning VOC [V] JSC [mA/cm2] FF (%) PCE (%)

Modules 1-2 PEROVSKITE CO2 LASER

3.27 -11.6 55.4 5.3 P3HT Chemical Etch

Modules 3-4 PEROVSKITE CO2 LASER

3.34 -12.1 66.1 6.7 P3HT CO2 LASER

Modules 5-6 PEROVSKITE

P3HT Nd:YVO4 LASER 3.36 -13.4 77.8 8.2

Mudules 7-8 PEROVSKITE

SPIRO Nd:YVO4 LASER 4.21 -18.7 66.5 13.0

CO2

Laser patterning

10.1 cm2 active area

F. Matteocci al. Prog. Photovoltaics (2014) DOI: 10.1002/pip.2557

Nd:YVO4

Laser patterning

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Scaling-up issues: losses in FF and ISC

Scaling-up: perovskite solar modules

F. Matteocci, et al PCCP, 16 , 3918

PCE=5.1%

• Deposition Uniformity on the active

area

Active area = 10 cm2

Power= 130 mW

Spin coating

deposition F. Matteocci et al.- Prog. Phot. 24, 436 DOI: 10.1002/pip.2557

PCE=13.0%

Double step

deposition

16.8cm2

PCE=13%

Optimized

Laser

Patterning

• High series resistance

W. Qiu et al.-En. Env. Sci. 9, 484 DOI: 10.1039/C5EE03703D

PCE=14.9%

Single step

Active Area= 4 cm2

Power= 54 mW

Spin coating

deposition • Several recombinations paths .

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How far can we go with spin coating ?

Module type Electrical parameters

VOC (V) I (mA) FF (%) PCE(%)

Spin-Coated / Two step 8.23 -118.05 62.4 12

0 2 4 6 8

-120

-90

-60

-30

0

Cu

rren

t (m

A)

Voltage (V)

Substrate area 100 cm2

Active Area = 60cm2

Efficiency on Active Area = 12%

10 cm

10 cm

A. Agresti et al. submitted

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From modules to MODULES

10 x

10 cm2

100 cm2

?

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From spin coating to air-assited blade coating

SPIN 10 M. SPIN 30 M. BLADE 10 M. BLADE 30 M.0.0

0.2

0.4

0.6

0.8

1.0

1.2

Vo

c (

mV

)

SPIN 10 M. SPIN 30 M. BLADE 10 M. BLADE 30 M.0

5

10

15

20

Js

c (

mA

/cm

2)

SPIN 10 M. SPIN 30 M. BLADE 10 M. BLADE 30 M.0

2

4

6

8

10

12

14

PC

E (

%)

SPIN 10 M. SPIN 30 M. BLADE 10 M. BLADE 30 M.0

20

40

60

80

FF

(%

)

0.0 0.2 0.4 0.6 0.8 1.0 1.2

-20

-15

-10

-5

0

Jsc (

mA

/cm

2)

Tensione (V)

J (3.3 - Blade)

J (2.3 - Spin)

Blade 13.3%

Spin 12.1%

A new high performing air-assisted blade coating technique for perovskite printing

Two-step deposition

Small area

Glass

air

blade

PbI2

S. Razza et al. J. Power sources 277, 286 (2015)

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Active area:100 cm2

PCE= 6.2 %

Power= 610 mW

Low quantity of solution required:

• Reduction of exposure to toxic agents

• Cost saving

Deposition over large area substrate:

• Control of deposition temperature

• Uniform deposition of active layer

Blade Coating deposition for large area

S. Razza et al. submitted

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23

Device’s energy band diagram

GO in inverted PSCs

Z. Wu et al., DOI: 10.1039/c4nr03181d

G. Kakavelakys et al., DOI: 10.1021/cm502826f

GO Working Function (WF)

Rate constant (e-) = 0.11ns-1 e-

Rate constant (h+) = 0.06ns-1

GO hole

conductivity:

105 S cm-1 K. Pydzinskaet al., DOI: 10.1002/cssc.201600210

Graphene Oxide as interlayer in PSCs

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Incident Photon to current

Conversion Efficiency (IPCE)

Absorbance

Current-Voltage (I-V) Characteristics

GO interlayer: Small area devices

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Shelf life

IPCE

VOC rise profile

Dark I-V

Improved charge injection

Improved Perovskite/Spiro interface Improved charge injection and/or collection

Improved long-term stability

GO interlayer: Small area - Transient

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Perovskite/GO/Spiro-MeOTAD - module showed improved PCE with an overall Pmax= 885 mW - Improved stability

VOC ISC FF PCE Pmax

Ref 8.96 114.2 59.9 6.21 612.8

GO 9.40 142.9 65.8 9.03 883.8

Graphene based module

PCE

S. Razza et al. submitted

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Spray coated PEDOT back electrode

Module Jsc [ma/cm2]

Voc [V]

FF [%]

PCE [%]

PEDOT 9.56 7.99 41 3.47

PEDOT/Au 9.57 7.25 60 4.67

Full bladed module with PEDOT as back electrode

S. Razza et al. submitted

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P1: Nd:YVO4, λ=1064 nm, 15 ns pulsed laser on FTO 44 μm wide scribing 200 μm wide spacing area P2: Nd:YVO4, λ=532 nm, 15 ns pulsed laser on SnO2/perovskite/HTM 700 μm wide etching 200 μm wide spacing area1 P3: Nd:YVO4, λ=532 nm, 15 ns pulsed laser 50 µm wide scribing

P1-P2-P3 on c-SnO2 Perovskite Solar Modules

P1-P2-P3 helps to increase the conversion efficiency on the aperture area (active area + interconnection area)

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Sol-gel deposited c-SnO2 not efficient as c-TiO2

but easily permits P1-P2-P3 16,4 cm2 Active Area 18,95 cm2 Aperture Area 86,5% Aperture ratio PCE = 7.3% Aperture PCE = 6.31 %

P1-P2-P3 on c-SnO2 Perovskite Solar Modules

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Perovskite Solar Cell

Graetzel said: “If photo- and thermal stability as well as tolerance to humidity can be achieved, commercial application on the large scale appear to be feasible.”

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Stability issues

Thermal Stability

Environment Stability Light Stability

Issue: Moisture Effect Solutions: • Perovskite Composition • Sealing Procedure

Issues: Burn-in effect UV Degradation HTM Photo-oxidation Solutions: • UV Filter • Light Soaking up to

1Sun

Issues: Electrode Migration HTM dopants Solutions: • Morphology Control • Sealing • Polarization at MPP point

These degradation factors are present at the same time under real working conditions of the device. Moreover, in order to minimize the impact on the photovotaic parameters of each issue, it is crucial to separate each effects.

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Intrinsic Stability

• Moisture

• Temperature

• Light Exposure

• Shading

• Polarization

Perovskite Degradation: Optical and Electrical Properties Interface: Perovskite/HTM Sealing: H2O Barrier HTM Stability: Pristine and Doped with Additives

80°C in air

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Degradation Mechanism

The sealing procedure is required!

7.6%

4.7%

7.3%

3.5%

Light Beam Induced Current (LBIC) is a helpful and non-disruptive measeurement to evaluate the stability during the aging tests. Shelf Life test: 5-days (120h), unsealed device stored in uncontrolled air atmosphere. Device processing: Single-Step deposition P3HT used as a HTM

120h

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Sealing: Lateral Degradation

460h

730h 930h 1160h

260h 0h

Lateral Degradation due to the sealing failure appear since 260h .

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Encapsulation Strategy & Stability

Article in press (Nano Energy)

• No effect of the sealing on the initial PV

performance

• Kapton adhesive film was laminated on the

device as primary sealing then a protective

glass was sealed to the device using a

methacrylate glue.

• An edge sealant was used to protect the

edge of the protective glass to limit the

moisture entrance.

SP-DES SP-D

Kapton

Adhesive

Light-curable

Glue

UV-curable

Glue as

edge

sealant

PSC

Device

Protective

Glass

F. Matteocci et al. NanoEnergy (2016) DOI: 10.1016/j.nanoen.2016.09.041

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Investigation on Sealing Procedure

All Sealing Procedures are realized in air

The effect of sealing is mainly related to the curing processes

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Stability: 1cm2 device

Main Issues: Deposition Uniformity (Jsc) TCO resistivity: (FF, Rs) HTL Properties (Voc) Architectures: Planar vs Meso Cost: Gold Replacement Safety: Lead content

Statistical investigation is needed

12 14 16 180

4

8

12

16

20

Coun

t

PCE (%)

0.1cm2

1.05cm2

Average PCE: Small Area (65samples) = 15% Large Area (23samples) = 13.6% Modules (3 samples) = 11.3%

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Accelerated Life Time Tests

ISOS-D-1 Shelf: Mechanical Stability

ISOS-D-1-2 High Temp: Thermal Stability

ISOS-D-3 Damp: Humidity Test

ISOS-O-1: Light Stability

F. Matteocci et al. NanoEnergy (2016) DOI: 10.1016/j.nanoen.2016.09.041

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Humidity Test

13.2% as initial PCE value RH = 95% T= 40-50°C

0.0 0.2 0.4 0.6 0.8 1.0

-20

-16

-12

-8

-4

0

Cu

rren

t [m

A/c

m2]

Voltage [V]

0h_PCE=13.3%

6h_PCE=12.1%

32h_PCE=10.6%

104h_PCE=10.4%Remarkable Voc decrease

F. Matteocci et al. Nano Energy (2016) DOI: 10.1016/j.nanoen.2016.09.041

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Thermal Stability: STEM-HAADF technique

In order to overcome the stability issues, it is vital to understand the degradation pathways of

the structures involved, which here are observed for the first time at nanometer-scale spatial

resolution in situ, inside a scanning transmission electron microscope (STEM), while the

composition is monitored with elemental mapping through energy-dispersive X-ray analysis

(EDX).

FIB Lamella TEM analysis EDX maps

doi:10.1038/nenergy.2015.12

Nature Energy Article number: 15012 (2016)

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A - double step - air vacuum conversion

B - double step - conversion in glovebox

C - double step - conversion in air (50% RH)

D - single step in glovebox

A B C D

500 nm

void

spiro

Perovskite capping layer

TiO2 scaffold

(with no

perovskite

infiltration)

Incomplete

perovskite

infiltration

Realization Procedures

doi:10.1038/nenergy.2015.12

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In-situ Heating

50°C 150°

C

200°

C

250°

C No change

in perovskite

layer until

150°C.

Leakage of iodine at the interface with perovskite and HTM

doi:10.1038/nenergy.2015.12

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In situ TEM analysis

Degradation starts after 150°C

Sample in vacuum

doi:10.1038/nenergy.2015.12

Nature Energy 15012 (2016)

doi:10.1038/nenergy.2015.12

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Ex-situ Analysis

• Not visible degradation occurs after

heating/cooling processes

• Reversible behaviour during the

thermal cycles

• The samples were carefully sealed

doi:10.1038/nenergy.2015.12

Nature Energy Article number: 15012 (2016)

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Light Soaking

0 50 100 150 200 250 3000

2

4

6

8

10

12

14

16

10.9%

*

P

CE

(%

)

Light Soaking Time (hours)

-0.018%/hour

*13.4%

T80=148 hours*

11.4%

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Stability on module 5.7x5.7cm2

-20

-15

-10

-5

0

0 1 2 3 4

Voltage (V)

Curr

ent density (

mA

/cm

2)

0.0 0.5 1.0 1.5 2.0 2.5 3.0

0

2

4

6

8

10

12

14

PC

Em

pp (

%)

Time (min)

11.2% Stabilized PCE

13% Reverse 11.2% Stabilized

Sealed

@White LED (350mA)

After Laser Ablation

Bladed Spiro

>350 hours

Burn-in effect

After Gold Evaporation

Task 1.2.2 D.11

Good

Uniformity

N. Yaghoobi Nia et al in preparation

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Lead content: Recycling Pb from Car Batteries

Lead content can be recycled from

exaust car batteries!

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Conclusion

• The Perovskite-based photovoltaic technology could be competitive with respect to CdTe and CIGS thin films in terms of cost and performance.

• Suitable for optoelectronic applications: LED, Laser, Solar cells • Our up-scaling process demonstrates the feasibility of the solution processed

PSC on large area substrates.

• The use of 2d-materials play a role at the interface of the p-i-n architecture.

• Encapsulation is mandatory to evaluate only the intrinsic dgradation factors

• Stability: Promising results but we have to solve some issues regarding the detrimental effect of the light exposure on the costituent materials and interfaces.

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Acknowledgments

MIUR

PRIN

DSSCX

AquaSol

Funds CHEETAH

DESTINY

GO-NEXTS

GRAPHENE-FLAGSHIP

FP7 CHEOPS

MOSTOPHOS

GRAPHENE-FLAGSHIP

H2020

Thank you for your

attention!