Supplementary material – Modelling transport in nanoparticle organic solar cells using
Monte Carlo methods
K. Feron,a,b,* S. Ulum,b N. Holmes,b A. L. D. Kilcoyne,c W. J. Belcher,b X. Zhou,b C. J.
Fell,a,b P. C. Dastoorb
a
CSIRO
b
c
Energy
Technology,
Newcastle,
NSW
2300,
Australia
University of Newcastle, Centre for Organic Electronics, Newcastle, NSW 2308, Australia
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720,
USA
*
Corresponding author email address: Krishna.Feron@csiro.au (Krishna Feron)
A. Simulation parameters
Table I. Simulation parameters used in the DMC model. Values are mostly tuned to describe
a P3HT:PCBM device.
Property
Value
Temperature (T)
300 K
Relative dielectric constant
3.1
Reference
1
Standard deviation density of
states electron donor and 0.05 eV
2
acceptor
3.65 nm (equivalent to 1D
3
Forster radius PCBM
diffusion length of 40 nm)
2.15 nm (equivalent to 1D
4
Forster radius P3HT
diffusion length of 8.5 nm)
(C60 diffusion length)
Exciton lifetime PCBM
11 µs
5
Exciton lifetime P3HT
400 ps
4
3 x 1012 s-1
6,7
3 x 1012 s-1
6,7
1 x 104 s-1
2
Reorganization energy
0.5 eV
2
Lattice constant
1 nm
6,8
Anode work function (ITO)
-4.8 eV
9
-4.08
10
-5.3
9
-4.3
9
Charge hopping rate constant
electron acceptor
Charge hopping rate constant
electron donor
Charge
carrier
Recombination rate
Cathode
work
function
(aluminium)
HOMO
electron
donor
(P3HT)
LUMO
electron
acceptor
(PCBM)
B. Film thickness – NP size relationship
A series of nanoparticle dispersion were prepared with the aim of determining the
film thickness – NP size relationship. NP size could be controlled through the P3HT:PCBM
concentration in water. A more concentrated solution would give a thicker film when
deposited using the same spin-coating conditions. The size of NPs in solution was determined
using DLS. The film thickness was measured using a profilometer. Figure S1 shows the
thickness as a function of NP size together with a linear fit that was forced to go through the
origin. The slope of the fit was approximately 3 indicating that each film consisted of 3 layers
of NPs.
FIG. S1. Film thickness as a function of NP size (red dots). A linear fit forced through the
origin (black solid line) had a slope of 2.92 ± 0.12 (standard deviation).
C. Optimisation of annealing conditions
Annealing conditions were optimised for efficiency. As shown in Fig. S2 an annealing
temperature of 140 ˚C and duration of 4 min. was found to be optimal.
Figure S2. Efficiency as a function of (a) annealing temperature while the annealing time is
fixed at 4 min. and (b) annealing time while the annealing temperature is fixed at 140 ˚C.
Blue dots indicate the average of 6 devices with standard deviation shown (error bars). The
black dots correspond to the maximum value of each set of devices.
References
1
P. Yu, D. Mencaraglia, A. Darga, A. Migan, R. Rabdbeh, B. Ratier, and A. Moliton, Phys.
Status Solidi C 7, 1000 (2010).
2
K. Feron, C.J. Fell, L.J. Rozanski, B.B. Gong, N. Nicolaidis, W.J. Belcher, X. Zhou, E.
Sesa, B. V. King, and P.C. Dastoor, Appl. Phys. Lett. 101, 193306 (2012).
3
P. Peumans, A. Yakimov, and S.R. Forrest, J. Appl. Phys. 93, 3693 (2003).
4
P.E. Shaw, A. Ruseckas, and I.D.W. Samuel, Adv. Mater. 20, 3516 (2008).
5
S. Cook, H. Ohkita, J.R. Durrant, Y. Kim, J.J. Benson-Smith, J. Nelson, and D.D.C.
Bradley, Appl. Phys. Lett. 89, 101128 (2006).
6
R.A. Marsh, C. Groves, and N.C. Greenham, J. Appl. Phys. 101, 083509 (2007).
7
L. Meng, Y. Shang, Q. Li, Y. Li, X. Zhan, Z. Shuai, R.G.E. Kimber, and A.B. Walker, J.
Phys. Chem. B 114, 36 (2010).
8
K. Feron, X. Zhou, W.J. Belcher, and P.C. Dastoor, J. Appl. Phys. 111, 044510 (2012).
9
Y.S. Eo, H.W. Rhee, B.D. Chin, and J.-W. Yu, Synth. Met. 159, 1910 (2009).
10
J.S. Foresi and T.D. Moustakas, Appl. Phys. Lett. 62, 2859 (1993).