Ether‐Functionalized Ammonium Salts to Enhance Electron Transport in n‐Type Conjugated Polymers

ABSTRACT Conjugated polymers (CPs) are promising solution‐processable semiconductors for fabricating next‐generation electronic devices. For the realization of highly performing CP‐based electronics, ionic additives have been considered to tune the morphology and charge transport of conjugated polymers. However, achieving high‐performance n ‐type CPs remains challenging because of their limited compatibility with ionic additives. Here, an ether‐functionalized ammonium salt (EGBr) was introduced as an additive for the benchmark n ‐type polymer, N2200, to improve miscibility and molecular ordering. The ether functionality facilitated homogeneous film formation, resulting in an enhanced electron mobility ( µ _e ) of 1.09 cm ² V ⁻¹ s ⁻¹ , compared with 0.510 cm ² V ⁻¹ s ⁻¹ for the alkyl‐based additive (HptBr) and 0.272 cm ² V ⁻¹ s ⁻¹ for the control. When employed as an electron‐transporting layer in organic photodiodes, EGBr‐incorporated N2200 enabled efficient electron extraction and suppressed interfacial recombination, yielding a shot‐noise‐limited specific detectivity ( D ^* _shot ) of 2.11 × 10 ¹³ cm Hz ^0.5 W ⁻¹ , outperforming the HptBr‐incorporated film (8.31 × 10 ¹² cm Hz ^0.5 W ⁻¹ ) and the control (3.79 × 10 ¹² cm Hz ^0.5 W ⁻¹ ). These results highlight that incorporating ether‐functionalized ionic additives is an effective strategy to enhance charge transport in n ‐type CPs and the performance of organic optoelectronic devices.