Effect of Dopant Properties on the Microstructures and Electrical Characteristics of Poly(3-Hexylthiophene) Thin Films

Effects of dopant properties on microstructures and the electrical characteristics of poly (3-hexylthiophene) (P3HT) films are studied by doping 0.1 wt% 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F₄−TCNQ), 6,6-phenyl-C₆₁butyric acid methyl ester (PCBM) and N,N'−Diphenyl-N,N'-(m-tolyl)-benzidine (TPD) into P3HT, respectively. The introductions of various dopants in small quantities increase the field-effect mobility and the I _on/I_off ratio of P3HT thin-film transistors. However, each of dopants shows various effects on the crystalline order and the molecular orientation of P3HT films and the performance of P3HT thin-film transistors. These can be attributed to the various size, shape and energy-level properties of the dopants.