Improved mobility of the copper phthalocyanine thin-film transistor

Copper phthalocyanine (CuPc) organic thin-film transistor (OTFT) was fabricated by thermal evaporation deposition on p-SiO2 dielectric layer. Organic thin-film transistors used in large display areas need the enhancement of transistor performances by increasing the Ion/Ioff ratio and the mobility. The output and transfer characteristics of CuPc-OTFT having source/drain interdigitated-finger geometry were investigated. The mobility, Ion/Ioff ratio and inverse sub-threshold slope for the CuPc-OTFT were found to be 5.32 × 10−3 cm2 V−1 s−1, 1.94 × 104 and 2.5 V/decade, respectively. The interface state density of the transistor was found to be 3.73 × 1011 eV−1 cm−2 using the conductance-frequency method. The CuPc film indicated a homogeneous surface having 3.878 nm small roughness values as observed by atomic force microscope (AFM) measurements. The obtained results indicate that we have improved a CuPc-OTFT transistor with high mobility without being of any substrate treatment.