25th anniversary article: recent advances in n-type and ambipolar organic field-effect transistors.

The advantages of organic field-effect transistors, such as low cost, mechanical flexibility and large-area fabrication, make them potentially useful for electronic applications such as flexible switching backplanes for video displays, radio frequency identifications and so on. A large amount of molecules were designed and synthesized for electron transporting (n-type) and ambipolar organic semiconductors with improved performance and stability. In this review, we focus on the advances in performance and molecular design of n-type and ambipolar semiconductors reported in the past few years.