Conjugated Polymer Design for Optoelectronic Applications

Conjugated polymers are macromolecules characterised by alternating single and double bonds along their backbones, enabling delocalised π-electrons that confer semiconducting and photoresponsive properties. By judicious selection of monomer units, backbone planarity and side-chain functionality, researchers tailor optical band gaps, charge-transport characteristics and film microstructure to meet the demands of light-emitting diodes, solar cells, photodetectors and electrochromic devices. Central to this design is the donor–acceptor approach, in which electron-rich and electron-deficient building blocks are arranged to promote intramolecular charge transfer, thereby lowering the energy gap and enhancing light absorption across the visible and near-infrared spectrum. Heteroatom substitution—such as replacing sulphur with selenium or tellurium—further modulates frontier molecular orbitals and intermolecular interactions, fine-tuning mobility and stability. Control over polymer molecular weight, end-group capping and processing conditions combines with self-assembly strategies to establish favourable thin-film morphologies and domain purities. This versatile platform has global significance in the drive towards lightweight, flexible and printable electronics, offering sustainable alternatives to inorganic materials for next-generation energy harvesting, display technologies and optical sensing.

Research from Nature Portfolio

A comprehensive study has elucidated the redox chemistry of π-extended tellurophene motifs in conjugated polymers, revealing that oxidised tellurium centres exhibit strong coordination to solvent molecules or anions. This coordination traps positive charge on the chalcogen rather than delocalising it along the π-backbone, a behaviour that can be modulated by counter-ion choice and molecular architecture. When counter-ions are non-coordinating, oxidation delocalises over the conjugated system, offering a route to balance charge storage and transport. Insights into co-existence of coordination and delocalisation inform the rational incorporation of tellurophene units to optimise redox stability, charge mobility and optoelectronic performance in organic field-effect transistors and battery electrodes.

Conjugated Polymer Design for Optoelectronic Applications publication trend

The graph below shows the total number of articles in conjugated polymer design for optoelectronic applications across all publications each year (not limited to Nature Index journals).

Technical terms

π-Conjugation: Continuous overlap of p-orbitals along a polymer backbone allowing delocalisation of electrons and semiconducting behaviour.

Donor–acceptor polymer: A polymer composed of alternating electron-rich (donor) and electron-deficient (acceptor) units to induce intramolecular charge transfer and reduce optical band gap.

Band gap: Energy difference between the highest occupied and lowest unoccupied molecular orbitals, governing absorption onset and electronic conductivity.

Electrochromism: Reversible change in optical absorption and colour of a material under applied electrical potential, used in smart windows and displays.

References

1. Influence of the heteroatom on the optoelectronic properties and transistor performance of soluble thiophene-, selenophene- and tellurophene–vinylene copolymers. Chemical Science (2016).
2. Molecular weight and end capping effects on the optoelectronic properties of structurally related ‘heavy atom’ donor–acceptor polymers. Journal of Materials Chemistry A (2014).
3. Redox chemistry of π-extended tellurophenes. Communications Chemistry (2019).
4. Building Block Engineering toward Realizing High-Performance Electrochromic Materials and Glucose Biosensing Platform. Biosensors (2023).
5. Origin of Optoelectronic Contradictions in 3,4-Cycloalkyl[c]-chalcogenophenes: A Computational Study. Polymers (2023).
6. Conjugated polymers based on selenophene building blocks. Polymer Journal (2022).