posted on 2020-03-18, 14:48authored byAtri Sarkar, Abdulla Bin Rahaman, Tara Singha, Koushik Chakraborty, Sayan Prodhan, Tanusri Pal, Surajit Ghosh, Prasanta K. Datta, Debamalya Banerjee
Electrically
conducting matrix comprised of graphene and organic molecule is immensely
versatile and has a broad range of potential applications. Highly
soluble zinc tetra-tert-butyl phthalocyanine–reduced
graphene oxide (ZnTTBPc–RGO) blend samples have been synthesized
with different RGO concentrations (0–1 volume fraction). The
electrical conductivity of ZnTTBPc–RGO samples indicates a
percolating behavior with the three-dimensional percolation threshold
of ∼0.167 vol. fraction of RGO. Room temperature as well as
temperature dependent (100–320 K) photosensitivity (P) measurements go through a maximum at ∼0.33 vol.
fraction of RGO content (namely sample G). Calculated P values exhibit a decreasing trend with increasing temperature and
have been ascribed to enhanced scattering mechanisms. Resistivity
data suggest that the charge transport process of ZnTTBPc–RGO
is consistent with Efros–Shklovskii variable range hopping
mechanism at 88–320 K. Moreover, comprehensive measurements
on nonlinear absorption (NLA) of ZnTTBPc–RGO show a significant
enhancement in nonlinear optical properties compared to pure ZnTTBPc
when measured with ∼100 fs, 1 kHz laser pulse at 540 nm in
an intensity range of 37–130 GW/cm2. Comparative
measurements on P and NLA coefficient show highest
values for sample G compared to others along with faster electron
transfer rate, confirmed by femtosecond transient absorption spectroscopy
measurements. These results provide a way of characterizing ZnTTBPc–RGO
blend for optoelectronic device applications.