In memory of Professor Gilles Horowitz

We are presenting a themed collection in the Journal of Materials Chemistry C in memoriam of Prof. Gilles Horowitz, who sadly passed away on April 28th, 2022. In this collection, we cover the topics that have been at the core of the scientific activity of Gilles. As a very passionate, dedicated and much-loved scientist with a background in physics, he had a tremendous impact on the broad field of organic electronics, having been a pioneer in our understanding and design of organic field effect transistors, and generally providing insights into charge transport mechanisms in organic matter. His work influenced the fields of materials chemistry, bioelectronics and materials science by providing the mechanistic understanding and methods to exploit underlying solid-state physics phenomena.

Specifically, this themed collection in the Journal of Materials Chemistry C honours Gilles’ contributions in the following fields, where he had so much impact: (i) organic and large-area electronics, (ii) key applications of organic devices, (iii) molecular engineering of organic semiconductors, (iv) organic field effect transistors, (v) organic light-emitting devices, (vi) charge transport in organic matter, (vii) device modelling, (viii) organic semiconductor growth, (ix) organic biosensors, and (x) electrochemical and electrolyte-gated transistors.

We share the memory of Gilles with this collection! A eulogy written by Yvan Bonnassieux, Professor at the Ecole Polytechnique and Director of the LPICM Institute is reproduced below. We all will miss Gilles!

In memoriam of Prof. Gilles Horowitz It was with great emotion that I wrote this eulogy. Gilles Horowitz passed away in April 2022, at the age of 72. A former CNRS research director, he was one of the fathers of the broad organic electronics field, and many of us owe our scientific interest in this field to him. The richness and multiplicity of his results in this journal are clear proof of this.

With a background in solid state physics, he defended his 3rd cycle thesis in 1975 and his state thesis in 1981 on “Contribution à l’étude de la conversion photo électrochimique de l’énergie solaire sur électrodes semi-conductrices” (“Contribution to the study of photo-electrochemical conversion of solar energy on semiconductor electrodes”). In 1976, he joined CNRS as a research associate in the Energy Studies Department at CEA Saclay. In 1982, he joined the Laboratoire des Matériaux Moléculaires (LMM, UPR241) in Thiais and became a research fellow in 1983. It was in this laboratory, as part of the team headed at the time by Francis Garnier, that he made a major contribution, laying the foundations of organic electronics from 1982 onwards. Trained as a physicist, he gradually moved closer to chemistry as he embarked on the adventure of conducting polymers, which were the central focus of the team’s development. Along with a handful of other researchers worldwide at the time, he was strongly contributing to the emergence of what was to become “organic electronics” at the frontier between chemistry and physics. In 1990, he became CNRS research director. In 2000, he joined ITODYS (UMR7086), founding a new team called “Organic Electronics-Molecular Organization”, with research themes centered on new materials for organic electronics, molecular architectures at interfaces and device modelling. Following a fruitful collaboration with the LPICM laboratory (École polytechnique, UMR7647 CNRS) as part of an ANR project on organic pixel design (ORGAPIX 2005–2009), he decided to join this laboratory and École Polytechnique in 2010, becoming a pillar of the OLAE “Organic and Large Area Electronics” team.

Gilles Horowitz’s area of expertise was undoubtedly organic electronics, a field in which he acquired an outstanding international reputation. In the 1980s–1990s, he helped develop one of the world’s very first organic transistors based on sexithiophene, a thin-film transistor whose performance was greatly enhanced by the results of his systematic study of the relationship between organic film structure and the electrical properties of the resulting device.

A major part of his expertise covered the modelling of organic transistors. He was responsible for one of the first models of the physical and electrical behavior of these components, highlighting and explaining, among other things, the variation in charge carrier mobility with gate voltage. His model also made it possible to predict the enhancement of mobility by increasing the size of crystalline grains.

The expertise acquired by Gilles Horowitz has led to innovative projects involving high-potential applications, such as nanoscale transistors with a single self-assembled semiconductor layer; the synthesis of new electroluminescent materials for organic light-emitting diodes; the production of a demonstrator for a device consisting of organic diodes driven by a matrix of organic transistors; and the modeling of biosensors and OECTs (organic electro-chemical transistors).

Gilles Horowitz published 200 articles and more than 10 chapters in authoritative books and is the author of several patents. He was invited to numerous international and national conferences (over 50 invitations). A quick bibliometric analysis of his work shows that it is widely recognized: 44 of his articles are cited more than 100 times, 6 more than 500 times, and an article he published in 1998 as the sole author is cited more than 2000 times.

Interested in the possibilities of commercializing his discoveries, Gilles Horowitz has been active in the business world. He was a member of the advisory board for Plastic Electronic, a company based in Linz (Austria) which markets products based on organic electronics. Gilles was also scientific advisor to LITEN (CEA Grenoble) on the “Printronics” project, which aimed to develop an industrial sector for the manufacture of organic electronic devices using printing techniques.

At a time when microelectronics was triumphant, Gilles Horowitz committed himself to the development of organic electronics, which was quite a gamble and a sign of his visionary spirit, since the field is currently booming, attracting the interest of many laboratories and manufacturers. He was a trailblazer!

Committed to training through and for research, Gilles has supervised numerous thesis students and post-docs who now find themselves feeling a little ‘orphaned’.

For many years, Gilles Horowitz has delighted students, always seeking to motivate them and make the subject of organic electronics, at the frontier of physics and chemistry, accessible to them. Between 2000 and 2009, he taught at the Université Paris Diderot, including in the DEA SIRA “Surface, Interfaces: Reactivity, Adhesion” and in the Master MMS “Molécules, Matériaux, Surfaces” at the UFR de Chimie. As soon as he arrived at École Polytechnique, he also became heavily involved in teaching, first by setting up a PHY652B “Polymers for Photovoltaics” course, a master’s course he taught between 2012 and 2018. He has also created an online course, a MOOC, entitled “Plastic Electronics”, which is accessible on Coursera and has already been taken by over 10 000 students.

Discreet, perhaps even shy, sensitive, Gilles Horowitz was well versed in scientific and artistic culture. His curiosity led him to take an interest in many things. He practiced music at a very high level, playing piano and clarinet, and regularly went on tour during the summer with an orchestra! Endowed with great moral and intellectual rigor, Gilles Horowitz was a colleague who could be counted on in all circumstances. All these dimensions made Gilles Horowitz an extremely endearing colleague and, to say the least, a worthy heir to the Age of Enlightenment!

Thank you, Gilles, we miss you.

Yvan Bonnassieux

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