# Efficient n‐Doping of Organic Semiconductors via a Broadly Applicable Nucleophilic‐Attack Mechanism

## TL;DR

A new method for efficiently n-doping organic semiconductors is introduced, using a nucleophilic-attack mechanism that significantly improves conductivity and works across various materials.

## Contribution

A novel nucleophilic-attack n-doping mechanism is introduced, offering a broadly applicable and highly effective approach for organic semiconductors.

## Key findings

- n-Butyl lithium achieves high conductivity in C60 and PC61BM, with values of 1.27 S cm−1 and 2.57 S cm−1 respectively.
- The nucleophilic-attack mechanism is validated across diverse OSC materials and extendable to other dopants like tert-Butyllithium and sodium ethoxide.

## Abstract

The development of efficient and broadly applicable n‐doping strategies for organic semiconductors (OSCs) is crucial for advancing the performance of various organic electronic devices. Here, a novel nucleophilic‐attack n‐doping mechanism is unveiled that achieves exceptionally high conductivity in doped OSC films and demonstrates broad applicability across OSCs. The remarkable efficacy of n‐Butyl lithium (n‐BuLi) is highlighted in n‐doping C60 and PC61BM, achieving a conductivity of 1.27 S cm−1 and 2.57 S cm−1, respectively, which are among the highest reported values for these materials. The investigation reveals that the n‐BuLi anion interacts with electron‐deficient units in OSCs, generating a carbanion that facilitates efficient electron transfer for n‐doping. This mechanism is further validated across diverse fullerenes, polymeric, and small molecule OSCs, and is extendable to other high‐performance dopants such as tert‐Butyllithium (tert‐BuLi) and sodium ethoxide (NaOEt). Device studies show that n‐BuLi‐doped C60 enables substantially improved diode rectification, attributed to greater junction built‐in potential. These findings establish a unified chemical‐bonding‐based n‐doping paradigm, complementing existing electrophilic‐attack p‐doping concepts, and pave the way for achieving efficient doping of OSCs for advanced organic electronic applications.

A novel n‐doping mechanism for organic semiconductors (OSCs) is revealed, based on a nucleophilic‐attack reaction. Using n‐Butyl lithium (n‐BuLi) as a model dopant, this strategy achieves exceptionally high conductivity in C60 and PC61BM. The mechanism is broadly applicable to various OSCs and other nucleophilic dopants, establishing a new chemical‐bonding paradigm for efficient n‐doping OSCs.