Simultaneous Enhancement of Electron and Hole Mobility in <i>Para</i> ‐Azaquinodimethane‐Derived Polymer by Individually Applying Various Additives

Abstract

ABSTRACT Achieving simultaneous enhancement of electron and hole mobility in organic semiconductors (OSCs) using a single additive remains a significant challenge. In this study, we present a unique additive strategy that enables concurrent improvement of both n‐ and p‐type transport in an n‐dominant ambipolar polymer incorporating para ‐azaquinodimethane and diketopyrrolopyrrole. By individually applying various additives including ionic, p‐type, and n‐type compounds, we achieve unprecedented enhancements of both electron (∼400%) and hole (∼100%) mobility. Such parallel improvement is unattainable via conventional electron transfer mechanism. We ascribe this effect to optimized film morphology, reduced activation energy, and lowered contact resistance. To further elucidate additive‐induced variations in electronic structure and guide future molecular design, density functional theory calculations reveal that incorporating para ‐azaquinodimethane into the polymer backbone facilitates strong orbital coupling with additives. This coupling introduces additional charge transport pathways between polymer segments, enhancing both electron and hole transport along lamellar and π–π stacking directions. Our findings suggest promoting robust orbital coupling between host polymers and additives offers a promising strategy to concurrently boost electron and hole mobility in a single OSC, effectively circumventing traditional limitations associated with separate p‐ and n‐type additives/dopants.