Rational Molecular Design of Diketopyrrolopyrrole‐Based n‐Type and Ambipolar Polymer Semiconductors

Abstract

Diketopyrrolopyrrole (DPP)‐based polymer semiconductors have drawn great attention in the field of organic electronics due to the planar structure, decent solubilizing capability, and high crystallinity. However, the electron‐deficient capacity of DPP derivatives are not strong enough, leading to relatively high‐lying lowest unoccupied molecular orbital (LUMO) energy levels of the corresponding polymers. As a result, n‐type and ambipolar DPP‐based polymers are rare and their electron mobilities also lag far behind the p‐type counterparts, which limits the development of important p‐n‐junction‐based electronic devices. Therefore, new design strategies have been proposed recent years to develop n‐type/ambipolar DPP‐based polymers with improved performances. In this view, these molecular design strategies are summarized, including copolymerization of DPP with different acceptors and weak donors, DPP flanked aromatic ring modification, DPP‐core ring expansion and DPP dimerization. The relationship between the chemical structures and organic thin‐film transistor performances is intensively discussed. Finally, a perspective on future trends in the molecular design of DPP‐based n‐type/ambipolar polymers is also proposed.