Proceedings of the European Summer School of Photovoltaics 4 – 7 ...

a)
a)
transmissivity [%]
b)
60
50
40
30
20
10
0
200 400 600 800 1000 1200
wavelength (nm)
1% GNPC
0,25% CNT
1%GNPC +0,1%CNT
1%GNPC+ 0,05%CNT
b)
transmissivity [%]
90
80
70
60
50
40
30
20
10
0
200 400 600 800 1000 1200
wavelenght (nm)
0,1 % GNPB
0,3 % GNPB
0,5 % GNPB
Fig. 2. Transparency measurements
a)
Fig. 1. ITME image: a) graphene nanoplatelets GNP-B, 2-5 um, b) graphene
nanoplatelets GNP-C 2-25 um
To measure transparency optical spectrometer was used.
Length of emitted waves varied from 1200 to 200 nm, but waves
shorter than 300 nm were blocked by PET substrate. Prepared
samples were compared with samples containing 0,25 wt% multiwalled
carbon nanotubes (MWCNTs) and mixtures connecting
1wt% GNPs-C with 0,05 or 0,1wt%MWCNTs.
To verify the resistance of the conductive layer to cyclic bending
mechanical fatigue tests were conducted. Prepared samples
were compared with similar samples based on 0,25 wt%
MWCNTs in 8 wt% PMMA 10 um layer and with 160 nm ITO on
borosilicate glass.
Results
Transparency measurements
Using GNPs in screen printed layers allows wavelengths with
the same intensity pass through (in contrast to layers based on
CNTs). This interesting property is characteristic for the GNPs layers
and can by used in various types of sensors. Relatively high
transparency of the layer containing the filler of carbon nanotubes
for the waves in the upper measuring range is reduced by 50
percent for the wave length of 300 nm (Fig. 2a).
Layer of 1wt% GNPs-C + 0,05wt% CNT has resistance at
80 kΩ/□. Transparency of 32% is sufficient for this layer to serve
as an electrode for electroluminescent displays and shall be further
investigated as a possible fotovoltaic cell.
Layers with GNP B loading varying from 0,1% to 0,5% have
higher transmissivity. Resistance of 0,1 GNP B layer is 2,2 M Ω/□
98
b)
Resistance [kΩ/ □ ]
14
12
10
8
6
4
2
0
Results of mechanical fatigue tests.
0 10000 20000 30000 40000 50000 60000 70000 80000
number of cycles
2%GNPC
0,25% CNT
Fig. 3. Results of mechanical fatigue tests: a) ITO based samples,
b) comparison MWCNT layers with GNPC layer
for layer based on Dupont 8155 matrix. Layers with PMMA-based
matrix have resistance of 1,5 M Ω/□. High transparency of
75…80% will allow to print layers on elastic photovoltaic applications
such as transparent conductive layers supporting classic
electrodes.
Elektronika 6/2012