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

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.