The aim of the CONTREX project is to understand and control a particular type of photoexcited state in a class of material that have the potential to address the current worldwide problem surrounding clean energy generation.
Conjugated polymers are cheap, flexible, plastic semiconductors that can be used in a wide variety of applications, one of the most important of which is solar cell technology. Conjugated polymers offer the potential of thin, flexible devices (such as solar cells or LEDs) which can be processed using low cost methods such as roll to roll printing. The performance of these materials is steadily improving with efficiencies across many devices becoming comparable to traditional inorganic counterparts.
However, in all of these devices and applications when they are being operated (either as a solar cell or as an LED) they result in the formation of a type of excited state known as a "triplet exciton". Triplet excitons are lower in energy than the more common Singlet exciton, and importantly they cannot absorb or emit light. Therefore, they traditionally are a major loss mechanism in organic solar cells and light emitting diodes reducing the overall efficiency of the device.
This project directly address the need for new materials for both clean energy generation AND more efficient energy usage. Conjugated polymers show great promise as novel materials for solar cell technology and thus by understanding and controlling the role that triplet excited states play in their constructions will allow for improvements in efficiency and stability. The know-how generated throughout this project is also relevant to organic LED technology which would result in more efficient and therefore greener light emitting devices.
This project has two main aims.
i) To synthesise materials to aid the understanding of triplet excitons and ii) to make us of them
Little is known about the properties of triplet excited states in conjugated polymers. By developing materials which allow for their detailed understanding we can further understand their role in the function of optoelectronic devices, leading to an increase in their performance.
Furthermore, triplet excitons possess unique properties which may lead to novel types of devices which have ultimate efficiencies higher than the current theoretical maximum. After understanding the properties of the triplet excited state we will develop new materials which can harness the power of the triplet excited state to produce new materials with unprecedented properties such as photon multiplication or upconversion.
