Transition metal-catalysed molecular n-doping of organic semiconductors

Abstract

Electron doping of organic semiconductors is typically inefficient, but here a precursor molecular dopant is used to deliver higher n-doping efficiency in a much shorter doping time. 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 (eta) 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, Pd-2(dba)(3)) catalyses the reaction, as assessed by experimental and theoretical evidence, enabling greatly increased eta 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).