Doping Versatile n-Type Organic Semiconductors via Room Temperature Solution-Processable Anionic Dopants

In this study, we describe a facile solution-processing method to effectively dope versatile n-type organic semiconductors, including fullerene, n-type small molecules, and graphene by commercially available ammonium and phosphonium salts via in situ anion-induced electron transfer. In addition to the Lewis basicity of anions, we unveiled that the ionic binding strength between the cation and anion of the salts is also crucial in modulating the electron transfer strength of the dopants to affect the resulting doping efficiency. Furthermore, combined with the rational design of n-type molecules, an n-doped organic semiconductor is demonstrated to be thermally and environmentally stable. This finding provides a simple and generally applicable method to make highly efficient n-doped conductors which complements the well-established p-doped organics such as PEDOT:PSS for organic electronic applications.