The field-effect mobility of the OTFT was calculated from the following equation
I_D=(W/2L) C_i ?(V_G-V_T )^2 (for the saturated regime) (1)
where ID is the drain current in the saturated regime, VG is the gate voltage, VT is the threshold voltages, W and L are the channel width and length, Ci is the capacitance per unit area of the gate dielectric layer, and µ is the field-effect mobility.
For measurement of the capacitance and leakage current, metal–insulator–metal (MIM) capacitors were fabricated comprising PNIPAM sandwiched between ITO (bottom) and Au (top) electrodes. The 15 wt% PNIPAM solution was spin-coated at 1000, 2000, 3000, or 4000 rpm and then baked at 85 °C for 40 min. The active area of the capacitor was 0.1 cm2. The dielectric constant was calculated using the equation
k=Cd/(?_0 A) (2)
where C is the capacitance, ?0 is the permittivity of a vacuum, d is the thickness of the film, and A is the active area of the capacitor.
