Context: Our interest is in the conducting or semiconducting polymers which might be used for light-emitting diodes, or for novel solar cells, or any of the other electronic applications of polymers. Our interest in insulating polymers includes the initiation of electrical breakdown, radiation damage processes, and the conversion of polymer precursors into diamond-like carbons. Electrode processes are a part of several of these areas.

Current activities: We emphasise two main themes. First, we are interested in the dynamics of carrier injection and motion, and in the processes which happen to the injected charge subsequently. These we model by self-consistent molecular dynamics (our CHEMOS code is a common tool). Secondly, we want to know how much performance can be improved by controlling the mesostructure (spaghetti-structure) of the polymer. Here we have developed a code which allows us to generate random polymer strands with chosen statistical properties (direction, straightness, cross-linking - all can be controlled and varied in chosen ways within a polymer block)

People involved (including external collaborators)

Dr Andrew Fisher (UCL), and Graham Conroy (who was a project student who carried out the mesoscopic modelling of polymer networks); Dr Tony Harker (UCL), more for similar calculations for insulating polymers. Dr Alison Mainwood (King?s College London) and Dr Barbara McKinnon (Monash University, Australia) for non-radiative transitions. Dr Marta Ramos (Universidado do Minho, Portugal; collaboration with Marta has covered a number of topics involving self-consistent molecular dynamics and Monte-Carlo methods of mesoscopic systems), Dr Alison Walker (Bath).

Dr Carl Griffiths (BICC Laboratories, Wrexham); Dr Claude LeGressus (CEA)

Recent (or simply relevant) papers

331. Electronic Processes at Interfaces Involving Conducting Polymers.
Marta M D Ramos, A M Stoneham, A P Sutton. 1994 Synthetic Metals 67 137-140.

348. Computational materials synthesis Ill: Synthesis of hydrogenated amorphous carbon from molecular precursors.
P D Godwin, A P Horsfield, A M Stoneham S J Bull, I J Ford, A H Harker, D G Pettifor and A P Sutton, 1996 Phys Rev B54 15785-15794

375 Modelling of diamond growth processes
A M Stoneham I J Ford P Chalker 1998 Mat Res Soc Bulletin 23 28-31

376 Elasticity and Plasticity of Diamond-like carbons
A M Stoneham, P D Godwin, A P Sutton & S J Bull 1998 Appl Phys Lett 72 3142-4

380 Charge Injection, Transport and Trapping in Polyacetylene
Marta M D Ramos and A M Stoneham 1998 pps 59-65 of Proceedings of the 3rd International Conference on Electric Charge in Solid Insulators 1998 Supplément à la Revue "Le Vide: science, technique et applications" No 287 (edited Gilles Damamme)

389 Mesoscopic Modelling of Charge Evolution in Conducting Polymers
M M D Ramos and A M Stoneham 1999; presented at the 1999 EMRS Spring Meeting.

Cross-links We are well aware of similarities to biological processes, and we are seeking to model some of those. The phenomena we are already treating link to the work on materials modification by electronic excitation which is a theme for several of us (Marshall Stoneham, Sasha Shluger, Noriaki Itoh). Andrew Fisher's work on polymers on semiconductors, partly in collaboration with Professor Andrew Briggs (Oxford).