More electronic materials opened up with new metal-organic framework

December 15, 2017

More materials for electronic applications could be identified, thanks to the discovery of a new metal-organic framework (MOF) that displays electrical semiconduction with a record high photoresponsivity, by a global research collaboration involving the University of Warwick.

Research published today in Nature Communications shows how high photoconductivity and semiconductor behaviour can be added to MOFs - which already have a huge international focus for their applications in gas storage, sensing and catalysis.

The new work, conducted by Universities in Brazil, the United Kingdom and France - including researchers at Warwick's Department of Chemistry - found that the new MOF has a photoresponsivity of 2.5 × 105 A.W-1- the highest ever observed.

The MOF has been prepared using cobalt (II) ions and naphthalene diimides and acid as ligands. The structure shows anisotropic redox conduction, according to the directions of the crystal lattice. The conduction mechanism is sensitive to light, and may be modified or modulated according to the incident wavelength.

Photoactive and semiconducting MOFs are rare but desirable for electrical and photoelectrical devices.

These results are the first of this kind concerning MOFs and are the starting point for the possibility of discovery of even more functional materials, displaying properties suitable for practical applications.

The potential for use in electronic components and photoconversion devices, such as solar cells and photocatalysts provides a very exciting future for such materials.

Professor Richard Walton, from Warwick's Department of Chemistry, commented:

"The material we have discovered paves the way for new applications of a topical family of materials in many areas ranging from technology to energy conversion. We illustrate how MOFs that combine organic and inorganic components can produce unique functional materials from readily available chemicals.

"Our work was underpinned by Warwick's strengthening collaborative links with Brazilian universities and our exceptional equipment for materials analysis "
The study was carried out with an international collaboration between the University of Warwick (UK), Universidade de São Paulo (Brazil), the Advanced Technology Institute at the University of Surrey (UK), and the University of Grenoble-Alpes (France).

Notes to editors:

The research, 'Electrical conduction modulated by light in a cobalt and naphthalene diimide metal-organic framework', is published in Nature Communications.

The collaboration between Universidade de São Paulo (Ribeirão Preto) and Warwick was initially funded by a Santander/Warwick Brazil Partnership Project in 2012 and led to a "special visiting researcher" position at Ribeirão Preto for Professor Richard Walton 2014-2018, funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico in Brazil (CNPq) to study the preparation of new functional materials.

This resulted in visits to Warwick by a number of Brazilian research students over the past 4 years, including Evandro Castaldelli, the first author of this paper. The research performed at Warwick made use of state-of-the-art equipment available in the X-ray Diffraction Research Technology Platform (currently directed by Richard Walton), one of eight such facilities to provide underpinning technologies for interdisciplinary research at Warwick to enable world leading research.

The University of Warwick & Brazil:

The University of Warwick has numerous significant links with Brazil - fostering key research collaborations, student recruitment in the country, and study abroad exchange programmes.

Warwick's lead partners in Brazil are the Universidade de São Paulo (USP), Universidade Estadual Paulista 'Júlio de Mesquita Filho' (UNESP) and the Federal University of Minas Gerais (UFMG) - with the Pontifical Catholic University of Rio de Janeiro (PUC-Rio) providing an opportunity for undergraduates to experience Brazil through Study Aboard.

There is a growing network of around ninety Warwick researchers who are currently engaged in some form of collaboration with Brazilian institutions.

University of Warwick

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