Fine-tuning of the metal work function by molecular doping

Abstract

A new approach for fine tuning of the metal work function (WF) in the range of 1 eV is described. WF control is achieved by 3D molecular doping of the metal rather than the classical 2D adsorption. Both small molecules (Congo red, thionine) and polymers (Nafion, poly(vinylbenzyltrimethylammonium)chloride) were shown to affect the work function of gold and silver. The in situ reaction of the dopants within the metallic matrix is a further tool for altering the WF, confirming that this effect is dopant-dependent. We attribute this effect to the charge transfer interactions between the dopant molecule and the surrounding 3D metallic cage.

Affecting an Ultra‐High Work Function of Silver

“…Recently we have introduced an entirely new methodology for affecting the WF of metals, namely the doping of the metal with WF‐modifying agents; that is, we move from derivatizing the 2D interface to the 3D volume of the metal. With this molecular doping we demonstrated the possibility to fine‐tune the WF of gold and silver within the modest range of up to 1 eV . Being a new approach and following the above cited theoretical predictions, we set to explore the possibility to utilize the doping methodology in order to push the WF of silver into the ultra‐high domain, which in the literature is defined as an increase of 2–3 eV .…”

“…The materials methodology of molecular doping of metals employed herein involves a variety of reducing processes of metal cations in the presence of the molecule or nanoparticle (NP) to be entrapped (see refs. for reviews and for recent examples). The resulting material is the metal in the form of tightly agglomerated nanometric crystals, incorporating the dopant molecule or NPs.…”

“…[11] Being anew approach and following the above cited theoretical predictions,weset to explore the possibility to utilize the doping methodology in order to push the WF of silver into the ultra-high domain, which in the literature is defined as an increase of 2-3 eV. [9][10][11] Them aterials methodology of molecular doping of metals employed herein involves av ariety of reducing processes of metal cations in the presence of the molecule or nanoparticle (NP) to be entrapped (see refs. [12,13] for reviews and [11,14,18] for recent examples).…”

“…[9][10][11] Them aterials methodology of molecular doping of metals employed herein involves av ariety of reducing processes of metal cations in the presence of the molecule or nanoparticle (NP) to be entrapped (see refs. [12,13] for reviews and [11,14,18] for recent examples). Ther esulting material is the metal in the form of tightly agglomerated nanometric crystals,incorporating the dopant molecule or NPs.The dopant is firmly held by the physical caging and by interactions between its functional moieties and the metallic surface of the nanocrystals that form the cages.I th as been repeatedly shown, in previous applications studies of this materials methodology,t hat this 3D architecture is completely different from regular 2D adsorption, and various specific applications,s uch as in catalysis, [17] biomaterials, [15,16] fuel cell, [14] and more, [18] are achieved only with the 3D entrapment.…”

Affecting an Ultra‐High Work Function of Silver

“…With this molecular doping we demonstrated the possibility to fine‐tune the WF of gold and silver within the modest range of up to 1 eV . Being a new approach and following the above cited theoretical predictions, we set to explore the possibility to utilize the doping methodology in order to push the WF of silver into the ultra‐high domain, which in the literature is defined as an increase of 2–3 eV . The materials methodology of molecular doping of metals employed herein involves a variety of reducing processes of metal cations in the presence of the molecule or nanoparticle (NP) to be entrapped (see refs.…”