Polymorphism mediated by electric fields: a first principles study on organic/inorganic interfaces

Area of Science:

• Surface science
• Materials science
• Physical chemistry

Background:

• Organic/inorganic interfaces exhibit polymorphism, with properties varying by structure.
• Polymorph formation depends on environmental factors like temperature and pressure.
• Many desired polymorphs are inaccessible under typical experimental conditions.

Purpose of the Study:

• To investigate the use of electric fields to control polymorph formation at organic/inorganic interfaces.
• To analyze how electric fields alter the energy landscape of interface systems.
• To demonstrate the accessibility of specific polymorphs using electric fields.

Main Methods:

• First-principles calculations
• Machine-learning based structure search algorithm
• Ab initio thermodynamics

Main Results:

• Electric fields can be used as an additional control parameter for polymorph formation.
• The energy landscape of the tetracyanoethylene (TCNE) on Cu(111) interface system is modified by electric fields.
• Electric fields can shift the phase transition temperature between standing and lying TCNE polymorphs by up to 100 K.

Conclusions:

• Electric fields offer a novel approach to tune and access specific polymorphs at organic/inorganic interfaces.
• This method enhances control over the properties of interface systems by manipulating structure.
• The findings pave the way for designing materials with tailored properties through electric field control.