Large Area Polymer Thin Film Towards High-Sensitivity BGBC-OFET Based Phototransistor

With the expansion of organic electronics, organic field-effect transistors (OFETs) are broadly used in electronic devices and logic circuits. In these, OFET-based phototransistors were recently developed for detecting the light signal. Developing better field-effect mobility and sensitivity in bottom gate bottom contact (BGBC) OFET-based phototransistors, however, is still a difficulty. This is because the low mobility of most organic photoresponsive materials limits the efficiency of transporting and collecting charge carriers. In the current work, a poly (3-hexyl thiophene) based organic phototransistor was studied. For increasing the device performance, a thin layer of Self-assembled monolayer (SAM) is formed on the dielectric interface of SiO2. The ribbon-shaped floating film transfer method (FTM) is utilized in the fabrication of thin film. The prepared film shows the average OFETs mobility, I-on/I-off ratio (mu) 2 x 10(-2) Cm-2/Vs, 10(4) respectively under air and dark conditions. This result is more than one order higher in the BGBC configuration reported by the conventional FTM. Further, illumination of light (lambda = 550 nm, Pin = 1 mW/cm(2)) shows photosensitivity of similar to 100 and responsivity of 22 AW(1).