[22p-P13-1~28] 12.1 Fabrications and Structure Controls

▲ [22p-P13-3] Investigating the role of hole doping in a p-type semiconducting polymer towards enhancing the field-effect mobility and photosensitivity

〇(D)Shubham Sharma¹, Subhajeet Jana², Rajiv Prakash², Shyam S. Pandey¹ (1.LSSE Kyutech, 2.IIT BHU)

Keywords:Hole Doping, Floating Film Transfer

Organic field-effect transistors (OFETs) are the basic building blocks of organic electronics. However, OFETs based on polymeric organic semiconductors exhibit poor performance owing to relatively hampered charge carrier mobility. This is not only due to their intrinsic semiconducting nature but also the presence of the mixed crystalline and amorphous domains controlling the charge carrier hoping. Recent advances in organic semiconductors and doping methods have shown that doping may also be a critical enabler for controlling the charge transport leading to enhanced device performance. In this work, the impact of a hole dopant utilizing a small dye molecule in a solution-processable polymeric semiconductor upon their implication on the charge transport has been examined. As a hole dopant, a NIR dye with a HOMO energy level lower than the p-type semiconducting polymer PB TTT-C14 was utilized. Dye-semiconducting polymer cocktail was prepared by mixing 1%, 2%, 5%, and 10% (w/v) of the dye with PBTTT-C14 in chloroform, followed by fabrication of their oriented thin films using the Floating Film Transfer Method (FTM). These oriented thin films in the presence and absence of dopants were utilized for OFET fabrication. It was observed the optical anisotropy in the thin films with 2% dye was highest as compared to that of the pristine PBTTT thin films. OFETs fabricated using oriented thin films of the dye-doped PBTTT-C14, demonstrated a 3-fold enhancement in the m from 0.1cm2/Vs for the pristine polymer to 0.3 cm2/Vs for the 2% dye-doped polymer. This is attributed to the fact that the dye molecule acts as the hole dopant resulting in the enhanced concentration of holes in the dye-doped thin films leading to 10 times increase in the on-current of the OFETs by the addition of the hole dopant dye molecules. Finally, the effect of NIR-based hole dopants on the photosensitivity of the device was also investigated by fabricating phototransistors.