To boost the solar cells’ light absorption, one of
the promising methods is to apply noble metal
nanoparticles, on which localized surface plasmon
(LSP) resonance can be excited under the light
illumination. The confined electromagnetic energy
based on LSP resonance could greatly improve the
light absorption of active medium surrounding the
nanoparticles (NPs) (Chen et al., 2013). The light
absorption enhancement and efficiency
improvement of different kinds of solar cells,
including thin film Si solar cells, dye-sensitized
solar cells (DSCs) (Qi et al., 2011), and organic
photovoltaics (OPVs) (Lu et al., 2013), had been
reported recently.
In present project, for the first time, localized
surface Plasmon effect of core-shell structure of
silver-alumina nanoparticles on photovoltaic
parameters of perovskite solar cells with planner
architecture based on Pb(CH
3
NH
3
)I
3
sensitizers, is
investigated. Performance of the devices are
evaluated by I-V measurement, cyclic voltammetry,
UV-Vis spectroscopy and electrochemical
impedance spectroscopy (EIS) and compared to
perovskite solar devices without LSP effect.
2 MATERIALS AND METHODS
The patterned substrates FTO were cleaned in an
ultrasonic bath, using detergent with de-ionized
water, acetone and isopropanol (10 minutes for each
step). Patterning of the TiO2 layer about 50nm was
achieved by using the dip coating method (multi-
purpose dip coating machine of Kimia Solar Co,
model: mpDCTT-1200). DektakVeeco 150
profilometer was used for measurement the
thickness of the blocking layer.
The lead iodide solution (PbI2 in N,N-
dimethylformamide, 460 mg ml-1) was made. Then
10 ppm silver-Alumina nanoparticles added in the
solution of PbI2, finally spin coated with 6000 r.p.m
for 10 sec then dried at 70 °C for 1 hr.
CH3NH3PbI3 crystallization was achieved by
dipping the PbI2 layer in a methylammonium iodide
solution (CH3NH3I in anhydrous 2-propanol 10 mg
ml-1) for 2 minutes then immediately washed with
2-propanol by spin coating method at 6000 r.p.m for
10 sec and dried at 70 °C for 30 min.
The hole-transporting layers was deposited by
spin-coating a 75 mg ml-1 solution of 2,20,7,70-
tetrakis-(N,N-dip-methoxyphenylamine)9,9’-
spirobifluorene (Spiro-OMeTAD), doped with 8 μl
of tert-butylpyridine and 11 μl of Lithium
Bis(Trifluoromethanesulfonyl)Imide (Li-TFSI)
solution (520mg in 1 ml of acetonitrile), was spin
coated by 2000 rpm for 45 second and thickness was
around 250nm (the thickness of all samples checked
by DektakVeeco 150 profilometer).
Samples were introduced into a high vacuum
chamber (10-6 mbar) to thermally evaporate Au
back contacts (thickness 80 nm).
Masked devices were tested under a solar
simulator (Kimia Solar sun simulator model: SSTT-
1100) at AM1.5G and 100 mW cm-2 illumination
conditions calibrated with a certified reference Si
Cell (RERASolutions RR-1002). Incident power
was measured with a Skye SKS 1110 sensor. The
absorbance was measured with a BLACK-Comet
UV-VIS Spectrometer. The morphology and grain
size of the PbI2, perovskite and HTM layers
obtained with Scanning Electron Microscopy (FE-
SEM). Electrochemical analysis was measured with
Autolab Instrument.
3 RESULTS
The Scanning electron microscopic images and UV-
Vis measurement of the perovskite layers shows in
the figures 1 and 2, respectively. The SEM shows
that the perovskite layer is quite homogenous and
the size of the crystal was around 100 nm. From the
UV-VIS measurement it observed with adding the
Silver-alumina nanoparticle as a dopant in the
perovskite the absorbance increased which is relate
to the LSP effect as we expect from the theoretical
investigation.
Figure 1: FE-SEM image of perovskite layer containing
Ag-Al
2
O
3
nanoparticles.