The role of atomistic simulations for hybrid
photovoltaics!
Alessandro Mattoni!
Istituto Officina dei Materiali
Istituto Italiano di Tecnologia
http://www.dsf.unica.it/~mattoni !
[email protected]!
39 070 675 4868!
Tel:
IIT Project: http://sites.google.com/site/polyphemoproject
A. Mattoni CNR-IOM Cagliari
Outline!
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Photovoltaic efficiency and materials science!
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Hybrid materials for photovoltaics!
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Atomistic approach!
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Show case applications:!
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Interlayers in polymer/metal oxide systems!
Hybrid perovskites!
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Efficiency / cost!
G.W. Crabtree and N. S. Lewis
Physics Today March (2007)
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x c($) 1 Pi c($)
=
=
Pi
y
A eff (%) Pi W
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Hybrid materials!
Noun: A thing made by combining two different element!
Adj. !Of mixed character; composed of different elements!
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Opposite requirements:!
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High performance (physical growth in vacuo, high
quality, ordered crystalline materials)!
Low cost (chemical synthesis in solution,
disordered, organic)!
Hybrid character reflects in complexity!
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Condensed Matter approach!
1!
d
| ψ >= −iH | ψ >
dt
| ψ, t >= e
iEt
| ψ, 0 >
< ψ |ψ >
H | ψ >= E | ψ >
1 2
e2
Ze 2
H = Σi − ∇ xi + Σi, j
+ Σi,k
2
| xi − x j |
| xi − X k |
d2
1
Xi = −
∇ Xi < ψ | H | ψ >
2!
2
dt
Mi
X(t)
Molecular dynamics!
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motivation for classical models!
d2
Xi M i = −∇ Xi < ψ | H | ψ >~ −∇ XiU(X)
2
dt
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Size effects (length and time)!
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Including temperature and thermodynamic effects!
Making the Microstructure complexity affordable by simulations!
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Understanding the core nature of the material (ionic nature vs.
covalent bonding)!
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Model potentials molecular dynamics!
d2
Xi = −∇ Xi < ψ | H | ψ >
2!
2
dt
~ −∇ XiU(X)
EP3HT /ZnO =
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Model potential for hybrids!
Saba, M. I., & Mattoni, A. (2015). Simulations of Oxide/Polymer Hybrids. In!
Encyclopedia of Nanotechnology !
(pp. 1–13). Dordrecht: Springer Netherlands. !
doi:10.1007/978-94-007-6178-0_100934-1!
Canesi, E. Energy Environ.
Sci. 2012, 5, 9068 J. Phys. Chem. C, 2014, 118 (9), pp. 4687
Mattioli, G. et al, Adv.
Energy Mater. 2014 23 settembre 2015, Roma!
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Example 1: pyridines!
2
Current density (mA/cm )
5
4
4-MP
3
2
1
P3HT only
TBP
0
-1
-2
0.0
0.2
0.4
0.6
0.8
Voltage (V)
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Example 2: Phthalocynanines!
C.Melis et al., ACS Nano, (2011)!
Metropolis montecarlo!
the long time scale (ms)
evolution of large
molecular aggregates!
………
µm!
size
energetics and the
intermediate time scale
(~ 100 µs) dynamics of
larger aggregates!
energetics and the
short time evolution
(~µs) of small ZnPc
dimers!
nm!
fs!
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ns!
………
µs
time
ms!
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Polymer/ZnPc/ZnO!
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Photogenerated h-e displacement!
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Photogenerated carriers lifetime!
Transient open
circuit voltage!
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ZnPC!
IV!
4nm!
15 nm!
Voc (V)!
0.61!
0.60!
0.71!
Jsc (mA/cm2)!
0.26 !
0.21!
0.17!
!
FF!
0.56!
0.54!
0.50!
PCE (%)!
0.09!
0.07!
0.06!
ZnO!
ZnO!
No !
ZnO!
P3HT!
P3HT!
P3HT!
J (mA/cm2)
0.25
0.15
0.05
−0.05
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
V (Volt)
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G. Mattioli et al. Adv. Energy Mater. 2014,
1301694 (2014)!
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Power conversion efficiency!
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Hybrid Perovskite
atomic/molecular scale mixing of organic molecules !
molecular levels are separated in energy from the optical gap!
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Electronic Structure!
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The MYP model for Methylammonium Lead Halide Perovskite!
d2
Xi M i = −∇ Xi < ψ | H | ψ > ~ −∇ XiU(X)
2
dt
UII
UOO
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GAFF force field for
methylammonium molecules !
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Ionic Matsui model for CsPbI3
Buckhingham!
Hybrid interactions built based on
LJ and Buckhingham!
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Mattoni, A.; Filippetti, A.; Saba, M. I.; Delugas, P. J. Phys. Chem. C 2015, 119, 17421–17428. !
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Rotational dynamics of the molecules!
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MYP versus ab initi molecular dynamics!
Theory (ab initio )!
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600
1.0e−10
300
Mosconi, E., et al. PCCP, 16, 16137. (2014) Quarti, C., Chem. Mater., 26, 6557
(2014)!
120
100
τ0
EXPM0
NMR
EXP IR
CPMD !
relaxation times (s)
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T (K)
200 150
1.0e−11
1.0e−12
M. Carignano et. al CP2K!
U. Roethlysberger, S. Meloni
CPMD!
1.0e−13
Frost, J. et al.!
Apl Materials, 2(8), 081506!
0
0.5
1
1.5
2
2.5
3
300/T K−1
Mattoni, A.; Filippetti, A.; Saba, M. I.; Delugas, P. J. Phys. Chem. C 2015, 119, 17421–17428. !
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Photoconversion efficiency (ideal limit)!
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PV Schockley
for a standard
seminconductor!
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I Interstitial defects !
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Conclusions!
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Atomistic simulations for understanding and
designing materials and interfaces for
photovoltaics!
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novel interfaces (e.g. pyridines and
phthalocyanines to improve polymer-metal
oxides) to improve efficiency!
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Understanding hybrid perovskites and solve
problems related to degradation and toxicity!
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Fundings!
Regione Autonoma della Sardegna
Istituto Italiano di Tecnologia
Consiglio Nazionale delle Ricerche
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