Ultralow-Voltage Eco-Friendly Water-Induced LiOx/AlOx Bilayer Dielectric-Based OFET

This article demonstrates lithium oxide (LiO
$_{\text {x}}{)}$
and aluminum oxide (AlO
$_{\text {x}}{)}$
bilayer dielectric-based ultralow-voltage operable organic field effect transistors (OFETs). Both dielectrics are processed through the water instead of toxic organic solvents. We have used donor acceptor-based p-type polymer poly[2,5-(2-octyldodecyl)-3, 6-diketopyrrolopyrrole-alt-5,5-(2,5di(thien-2-yl)thieno [3,2-b] -thiophene)] (DPP-DTT) as an organic semiconducting (OSC) layer. The semiconducting layer was transferred employing the floating film transfer method (FTM), which has the benefits of large-area processing compatibility, low OSC material wastage, and no requirement for any costly equipment for film transfer. Water has been used as the liquid substrate for FTM instead of commonly used ethylene glycol and glycerol. The LiO
_x
/AlO
_x
/DPP-DTT OFET showed the maximum mobility (
$\mu _{\text {max}}{)}$
of 0.34 cm
$^{{2}}\,\,\text{V}^{-{1}}\,\,\text{s}^{-{1}}$
average mobility (
$\mu _{\text {avg}}{)}$
of 0.24 ± 0.06 cm
$^{{2}}\,\,\text{V}^{-{1}}\,\,\text{s}^{-{1}}$
, the threshold voltage of −0.25 ± 0.1 V, subthreshold swing (SS), and a trap density (
${N}_{\text {it}}{)}$
of 90 ± 11 mV/decade and 5.80
$\pm \,\,01.91\times 10^{{11}}$
eV
⁻¹
cm
⁻²
. The DPP-DTT OFET device is operable under −1 V and this ensures that the device can be switched across a narrow voltage range with a high ON/ OFF ratio of
$\sim 10^{{5}}$
.