Multi-component self-assembled molecular-electronic films: towards new high-performance thermoelectric systems

Area of Science:

• Materials Science
• Condensed Matter Physics
• Organic Electronics

Background:

• Thermoelectric materials convert heat to electricity.
• Organic molecules on surfaces show potential for flexible energy harvesting films.
• Quantum interference (QI) controls room-temperature transport properties.
• Constructive QI (CQI) in self-assembled monolayers (SAMs) enhances conductivity and Seebeck coefficients.
• Rigid electrode coupling limits current CQI-enhanced systems.

Purpose of the Study:

• To investigate enhancing cross-plane thermoelectricity in SAMs by incorporating additional molecular layers.
• To overcome limitations of rigid electrode couplings in CQI-enhanced SAMs.
• To develop a new strategy for designing advanced thin-film thermoelectric materials.

Main Methods:

• Combined experimental and theoretical study.
• Bottom-up assembly of multi-component thin-films.
• Utilized a 'sticky'-linker (alkynyl-functionalised anthracenes) and a 'slippery'-linker (functionalized metalloporphyrin).
• Fabricated anthracene-based SAMs and added porphyrin and/or graphene layers.

Main Results:

• Incorporating extra molecular layers enhanced cross-plane thermoelectricity in SAMs.
• Addition of a porphyrin layer or a graphene layer to anthracene-based SAMs increased the Seebeck coefficient.
• Combining both porphyrin and graphene layers resulted in a further significant boost in Seebeck coefficients.
• Demonstrated the first Seebeck-enhanced multi-component SAMs.

Conclusions:

• Multi-component SAMs offer a new strategy for boosting thermoelectric performance.
• The approach allows for enhanced Seebeck coefficients without compromising electronic features.
• This work opens avenues for designing improved flexible, solution-processed thermoelectric thin-films.