Universal and Efficient p-Doping of Organic Semiconductors by Electrophilic Attack of Cations

TL;DR

This paper introduces a universal, efficient p-doping mechanism for organic semiconductors using electrophilic attack by trityl cations, enabling high doping efficiency across various OSCs with high ionization energies.

Contribution

It reveals a novel doping mechanism involving electrophilic attack by trityl cations, expanding doping applicability to a wider range of OSCs with high ionization energies.

Findings

Achieved 100% polaron yield efficiency in P3HT.

Doped various OSCs with high ionization energy effectively.

Doping efficiency over 80% in P3HT.

Abstract

Doping is of great importance to tailor the electrical properties of semiconductors. However, the present doping methodologies for organic semiconductors (OSCs) are either inefficient or can only apply to a small number of OSCs, seriously limiting their general application. Herein, we reveal a novel p-doping mechanism by investigating the interactions between the dopant trityl cation and poly(3-hexylthiophene) (P3HT). It is found that electrophilic attack of the trityl cations on thiophenes results in the formation of alkylated ions that induce electron transfer from neighboring P3HT chains, resulting in p-doping. This unique p-doping mechanism can be employed to dope various OSCs including those with high ionization energy (IE=5.8 eV). Moreover, this doping mechanism endows trityl cation with strong doping ability, leading to polaron yielding efficiency of 100 % and doping efficiency of over 80 % in P3HT. The discovery and elucidation of this novel doping mechanism not only points out that strong electrophiles are a class of efficient p-dopants for OSCs, but also provides new opportunities towards highly efficient doping of OSCs.