Figure 1

Charge carrier density as a function of distance from the semiconductor-gate dielectric interface $z$ in an OFET. In a semi-infinitely thick semiconductor, the charges distribute in 3D, resulting in a density that decreases with the square of the distance from the interface. In a monolayer semiconductor with a thickness $d_{\mathrm{sc}}$, the carriers are confined in 2D, and a constant carrier density is expected.Reuse & Permissions

Figure 2

(a) Experimental transfer curves of a P3HT field-effect transistor measured as a function of temperature, at a drain bias of $V_D=-2\mathrm{V}$. Curves calculated according to Eq. (5) are presented as black lines, using the following parameters: $T_0=402\mathrm{K}$, ${\sigma }_0=1.76\times {10}^6\mathrm{S}/\mathrm{m}$, ${\alpha }^{-1}=1.4\AA$, and $V_t=2.5\mathrm{V}$. The semiconductor thickness was 80 nm, and the width and length of the channel were $2500$ and $10\mu \mathrm{m}$, respectively. (b) The same experimental data as in (a) plotted on a double logarithmic scale, corrected for a threshold voltage of 2.5 V. The red lines are a power-law fit at high gate bias, for each temperature. (c) The power-law exponent $\gamma$ extracted from (b) versus inverse temperature. A similar analysis was performed on literature data reported for MDMO-PPV and PTV [18, 19]. The solid lines are a guide to the eye.Reuse & Permissions

Figure 3

(a) Experimental transfer curves of a SAMFET measured as a function of temperature, at a drain bias of $V_D=-2\mathrm{V}$. Curves calculated according to Eq. (8), based on a step-function carrier distribution, are presented as black lines. The following parameters were used: $T_0=627\mathrm{K}$, ${\sigma }_0=4\times {10}^6\mathrm{S}/\mathrm{m}$, ${\alpha }^{-1}=4.3\AA$, $V_t=-1\mathrm{V}$, and $W/L=20000/20$. The semiconductor thickness was taken as 2 nm. (b) The same experimental data as in (a) plotted on a double logarithmic scale. The red lines are a power-law fit at high gate bias, for each temperature. (c) The exponent extracted from (b) versus inverse temperature. Similar analysis was done for a T6 monolayer transistor, as presented in the Supplemental Material [17]. The solid lines are a guide to the eye. Extrapolating the monolayer data to infinite temperature does not agree with Eq. (6), as indicated by the dashed line.Reuse & Permissions