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Professor David Lidzey

Professor David Lidzey

Professor of Physics

Dept. of Physics & Astronomy

Hicks Building
Hounsfield Road
Sheffield S3 7RH

Room : D18
Phone : +44 (0)114 22 23501
Fax : +44 (0)114 22 23555


The Electronic and Photonic Molecular Materials group is based in the Department of Physics and Astronomy at the University of Sheffield.

We have a long-standing interest in many aspects of the physics and technology of organic semiconductors and organic optoelectronic devices. Current research programmes include study into organic light emitting diodes (LEDs), organic photovoltaic devices (PVs), organic field-effect transistors (FETs) and organic photonic devices.

Our work is conducted in a series of modern laboratories and clean rooms for device preparation and evaluation. Micro- and nano-scale devices and structures are also developed jointly with researchers in the III-V Central Facility at Sheffield. We have access to a range of spectroscopic techniques, including an ultra-fast laser facility and a range of scanning probe microscopes.

We have had a number of joint research projects, running with both UK and European Universities and also with UK and international companies commercializing organic electronics.

Organic Light Emitting Diodes

We have more than a ten years' research experience in the development of polymer LEDs. Our work has focussed on new methods to improve the optical efficiency of LEDs, and the evaluation of new polymeric materials for LED applications. We are also developing high-speed polymer LEDs for all-plastic data communication applications.

Our material development programme involves a close collaboration with Ahmed Iraqi in the Department of Chemistry at Sheffield. Together, we have worked on a new class of polymers called poly(alkylcarbazoles), which are blue emitting polymers that can have good hole mobility and improved colour-stability under photooxidation (e.g. see chemical structure in figure 1(a)). These materials can be synthesized with high molecular weight and having blue fluorescence and an ionization potential of 5.0V, making them promising candidates as host materials for LED applications. More recent work has explored 2,7-linked carbazole polymers functionalized at the 9-position with a triaryl amine moiety (see fig 1(b)). This substitution is anticipated to further increase hole mobility.

Organic photovoltaics

Organic semiconductors are currently the subject of intense interest for their application in photovoltaic devices (solar cells). When light is absorbed by the organic photosensitive material, an excited state can be formed termed an exciton. This state can be separated into an electron-hole pair before it recombines emitting a photon. This is done in many organic photovoltaic devices by blending two materials together; one of which accepts the electron, and the other the hole. We are currently exploring a range of different materials in photovoltaic devices; here, our interest is both to understand the mechanisms that limit device efficiency and also develop more efficient devices.

The limited red sensitivity of organic photovoltaic devices is thought to be a key reason explaining their relatively low power conversion efficiency - clearly developing devices that can absorb light at longer wavelengths is a useful strategy to improve device efficiency. To address this issue, we have been exploring the properties of new red-absorbing materials synthesized by Ahmed Iraqi in the Department of Chemistry at the University of Sheffield. velengths.

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University of Sheffield
Dept. of Engineering Materials
Sir Robert Hadfield Building
Mappin St.
Sheffield S1 3TD

tel +44 (0)114 2225506
fax +44 (0)114 2226015

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