Transition metal-catalysed molecular n-doping of organic semiconductors

Chemical doping is a key process for investigating charge transport in organic semiconductors and improving certain (opto)electronic devices^1–9. N(electron)-doping is fundamentally more challenging than p(hole)-doping and typically achieves a very low doping efficiency (η) of less than 10%^1,10. An efficient molecular n-dopant should simultaneously exhibit a high reducing power and air stability for broad applicability^1,5,6,9,11, which is very challenging. Here we show a general concept of catalysed n-doping of organic semiconductors using air-stable precursor-type molecular dopants. Incorporation of a transition metal (for example, Pt, Au, Pd) as vapour-deposited nanoparticles or solution-processable organometallic complexes (for example, Pd₂(dba)₃) catalyses the reaction, as assessed by experimental and theoretical evidence, enabling greatly increased η in a much shorter doping time and high electrical conductivities (above 100 S cm⁻¹; ref. ¹²). This methodology has technological implications for realizing improved semiconductor devices and offers a broad exploration space of ternary systems comprising catalysts, molecular dopants and semiconductors, thus opening new opportunities in n-doping research and applications^{12, 13}.