C.T.S.G. Alembic

Electrosynthesis of ultra-thin molecular films for solid-state dynamic molecular switches.

With the rapid-increase in miniaturized electronics, there is a drive to develop electronic devices in nanoscale dimensions.  In this context, molecule-based electronic devices are appealing that can mimic conventional silicon-based circuits because of their inherently small size, tunable electronic properties, and easier synthesis process.

In this regards, dynamic molecular switches are attracting that undergo continuous transitions from ON to OFF states under external bias and remember its history. So far the reported literatures primarily utilized conventional self-assembly approach often leading to poor binding between molecules and bottom electrodes and stability issue, thereby limiting the effectiveness and durability of the devices.  

In this project, we opt for electrochemical grafting approach to grow robust molecular thin film.

The current interdisciplinary project includes multiple steps which are outlined below.

1. Synthesis of in-situ or ex-situ diazonium salts from respective amine precursors, see Figure 1a.
2. Electrochemical (E-Chem) grafting of generated diazonium salts on gold (Au) substrate. The E-Chem approach can  covalently bind the molecules with the Au surface, thus can enhance the stability of the thin film (Figure 1b). Nitrogen on the thin film can be further responsible for slow proton-coupled electron transfer (PCET), which can show dynamic ON and OFF states.
3. Characterization of fabricated thin films via atomic force microscopy, static water contact angle, and X-ray photoelectron spectroscopy. This can illustrate how well-ordered, homogenous, and less rough molecular thin films are.
4. Electrochemical techniques (cyclic voltammetry, differential pulse voltammetry and impedance spectroscopy) to probe PCET in the grafted substrates. Further electrochemical studies at different temperatures and pH can assist in examining the kinetics of PCET.
5. Current-voltage (I-V) measurements with EGaIn as top electrode to investigate their dynamic switching characteristics (Figure 1c).

These systematic research works can provide roadmap for future research work aiming to fabricate high-yield,  stable and scalable molecular electronic devices.

Contact info:

Supervisor:
Christian Nijhuis, c.a.nijhuis@utwente.nl

Daily Supervisor:
Ritu Gupta, r.gupta-1@utwente.nl