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PGI Colloquium: 

Prof. Dr. Dominique Vuillaume,
IEMN Unité Mixte de Recherche CNRS, Université des Sciences et Technologies de Lille, France


PGI Lecture Hall, Building 04.8, 2nd Floor, Room 365

29 Jan 2016 11:00

Dynamics in molecular devices: switch, memory, memristor and synapstor

I will review some of our results on dynamic processes in molecular electronics, coupling optical and electronics properties in molecular junctions and hybrid molecule/gold nano-particle self­assembled networks.

First, I will discuss a new azobenzene-bithiophene (AzBT) molecular optical switch designed, synthesized, and used to form self-assembled monolayers (SAM) on gold with a “on/off” conductance ratio up to 7x103 [1]. These molecules can cap gold nanoparticules (10 nm in diameter) and form Nano-Particle Self-Assembled Networks (NPSANs). Electrical measurements [2] show repeatedly a conductance switching of NPSANs upon UV/blue irradiation with typical “on/off” ratios up to 500, improving previous literature results. I will also present recent results of NPSANs with redox molecules exhibiting giant NDR (negative differential resistance) and memory effect [3]. I will discuss how these NPSANs can be tentatively used in reconfigurable circuits with leaning capability.

Secondly, I will present an artificial synapse, an organic synapse-transistor (synapstor) working at 1 volt and with a typical response time in the range 100-200 ms. This device (also called NOMFET, Nanoparticle Organic Memory Field Effect Transistor) combines a memory and a transistor effect in a single device [4,5]. We demonstrate that short-term plasticity (STP), a typical synaptic behaviour, is observed when stimulating the device with input spikes of 1 volt. Both significant facilitating and depressing behaviours of this artificial synapse are observed with a relative amplitude of about 50% and a dynamic response < 200 ms [6]. This device acts as a memristive device.

Finally, an electrolyte-gated organic synapstors (EGOS) working at very low voltage will be presented. The EGOS exhibits STP behaviour with a useful relative amplitude (0.3-­‐0.5) for spike amplitude down to 50 mV (on a par with the action potential in neurons). Preliminary results show that neural cells cultures (adhesion, proliferation and differentiation) are successfully developed on EGOSs. The performances of the EGOS are not strongly affected by the growth of neural cells [7].

I will discuss the implications of these results for the development of neuro-inspired computing architectures and interfacing with biological neurons.

[1] K. Smaali et al. ACS Nano 4, 2411-­‐2421 (2010)
[2] Y. Viero et al. J. Phys. Chem C. 119, 21173-­‐21183 (2015).
[3] T. Zhang et al., Eur. Conf. Mol. Elec. , Strasbourg (2015) & Int. Conf. Org. Elec., Erlangen (2015).
[4] F. Alibart et al., Adv. Func. Mater. 20, 330-­‐337 (2010).
[5] F. Alibart et al., Adv. Func. Mater. 22, 609-­‐616 (2012).
[6] S. Desbief et al., Organic Electron. 21, 47-­‐53 (2015).
[7] S. Desbief et al., Eur. Conf. Mol. Elec., Strasbourg (2015).


Prof. Dr. Paul Kögerler
Phone: +49 2461 61-3159
Fax: +49 2461 61-2620
email: p.koegerler@fz-juelich.de