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Photovoltaic materials from novel self-assembling nanostructured liquid crystals

Final Activity Report Summary - LC-ENERGY (Photovoltaic materials from novel self-assembling nanostructured liquid crystals)

Generation of electricity from light is a complex process of multiple sequential steps: first the light should be absorbed by the material, generating a high energy electron-hole pair. This pair needs to be separated in an electron and a hole; that will move towards the electrodes of the solar cells using their own pathways. However, the mobility of the pair is very low (10 nanometres), which means that successful separation only occurs at the interface of the two different pathways. Secondly the electron and hole need to be transported to the appropriate electrodes using separate highly efficient conductive pathways that never meet another (to avoid recombination). This entire process requires a highly defined morphology of the active components in the material. In practice, however, there is no controlled nanomorphology present in organic photovoltaics.

The goal of LC-ENERGY was to introduce a new concept in organic photovoltaic (solar cell) materials, particularly in their nanomorphology. To this end, we have modelled, prepared and investigated a series of different materials, based on organic dyes in a well-defined geometry. After a number of different approaches, we arrived at a series of materials that show very promising results. The photovoltaic behaviour (solar cell efficiency) of these materials are currently under investigation at the University of Cambridge (group of Prof. Richard Friend).

Apart from the work on liquid crystal-based photovoltaics, other projects using liquid crystals to control the nanomorphology have been targeted too during the fellowship. They include ionic liquid crystals (the first full structure-properties relation was published by us) for template polymer growth; platinum-based liquid crystals for one-dimensional conduction and sensor applications and holographic polymer-dispersed liquid crystal devices for tuneable photonic crystals (used for switching devices in telecommunication or for example for tuneable lenses), where we obtained a world record switching speed with reduced power consumption!