Two-dimensional conjugated polymers for photosensitive devices

Project content and funding

This project aims to study the charge transport properties in two-dimensional conjugated polymers (2DCP) and explore their capabilities for application in flexible electronic devices. In this scope, we will examine the effect of processing parameters on the transport properties of a set of 2DCPs. By varying thin film deposition parameters, we will influence the crystallinity of the 2DCP films and interconnectivity of polymer segments, this will directly affect the charge transport properties of thin films. It is expected that the extension of polymer dimensionality into two dimensions will improve the alignment of individual polymer sheets and overcome the limitations associated with the unfavorable alignment of one-dimensional polymer chains.

Flexible electronics is a technology associated with the fabrication of electronic devices on flexible substrates such as polyamide, PEEK, polyethylene, paper, textile, and even stretchable elastomeric substrates. While conventional (inorganic) semiconductors can be to some extent made flexible by thinning the wafers or using polycrystalline forms (for example Si monocrystal wafer vs. polycrystalline Si), the electronic devices in applications that require bending, rolling, folding, and stretching cannot be fulfilled by conventional components. There is a growing interest in developing new materials and fabrication techniques that enable the fabrication of up-scaled electronic devices directly onto flexible substrates, enabling devices that can adapt to complex and dynamic surfaces. This will open the door for exciting new applications such as flexible lighting and display technologies for consumer electronics, architecture, and textiles; sensors and implantable electronics that will help monitor our health habits and improve medical diagnostics; as well as extending the functionality of robots and other instruments for work under severe mechanical stress. In addition to easy processability and high robustness to deformation, the materials for flexible electronics should ideally be low-cost, thin, and disposable.

To overcome the limitations of interchain charge transfer, in recent years, attention was given to polymers that extend the π-conjugation to two dimensions, which should be inherently less susceptible to disorder-induced localization. Two-dimensional conjugated polymers have been described and accepted as crystalline, single- to few-layer polymer films/nanosheets prepared via 2D covalent polymerization that exhibits strong in-plane π-electron delocalization along with two orthogonal directions and weak out-of-plane π-π stacking. Compared to conventional two-dimensional materials (for example graphene or transition metal dichalcogenides), 2DCPs retain a high level of chemical design flexibility and are compatible with solution processing. Because the synthesis of good quality 2DCP thin films is quite novel the correlation between charge transport physics and 2DCP properties such as grain size, crystalline domain sizes, grain boundaries, and edge structures remains to be explored.

Project Funding: Project is funded by Slovenian Research Agency (Project number: Z1-3189).

Project duration: 1. 10. 2021 – 30. 09. 2023

Project phases

WP1: Charge transport in 2DCP thin films
Morphology and structure characterization of 2DCP thin films
TOF characterization of as-deposited thin films deposited 
Annealing of thin films, and identification of their morphology and structure
TOF characterization of as annealed thin films deposited
OFET characterization of best-performing thin films
Identification of polymer-polymer interactions by 2D IR)
WP2: Charge transport on a local scale 
CAFM characterization of local scale conductivity in 2DCP thin film
KPFM characterization of local scale electric potential in 2DCP thin film
TOF characterization using SNOM 

Project team

Doc. Dr. Nadiia Pastukhova  SICRIS

The core of the research work will be done in the Laboratory of Organic Matter Physics at the University of Nova Gorica (UNG), Slovenia, 2DCPs will be synthesized by Chair for Molecular Functional Materials, Center for Advancing Electronics Dresden, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Germany, 01069 Dresde, Alemania, Dresde, Germany.

Project results

[1]N. Pastukhova, K. Liu, R. Dong, G. Bratina, X. Feng, and E. Pavlica, “Photoexcited charge mobility in quasi two-dimensional polyacetylene,” Organic 2D Crystallyne Materials: Chemistry, Physics and Devices (O2DMAT). nanoGe, p. 1, 2022. [Online]. Available: https://www.nanoge.org/proceedings/O2DMAT/62b0a8aacee4c129dd9411d8