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Project: Materials for green processing and their integration in low cost organic photovoltaic cells

Acronym: GreenSOL
Main Objective: The main objective consist of replacing the organic semiconductors utilized in state-of-the-art OPV cells, by new materials, with advantageous properties, namely, higher efficiency, lower cost, morphologic stability, and solubility in water or environmentally friendly solvents (ex. water or ethanol). The solubility in environmental friendly solvents will decrease the toxicity of the cells fabrication process. In a large scale cells fabrication, the solvents used for the present devices, being aromatic solvents, are not viable.

The new ink formulations developed under this project will then be adequate for large-scale coating green processes. Thus, ultimately we aim at demonstrating OPV cells exhibiting efficiency levels sufficient for commercial applications (10 % or higher) while involving reduced fabrication costs, and eliminating toxic organic solvents from the cells fabrication process.

The proposed new organic materials will be n-type organic semiconductors, with electron-acceptor character, capable of being processed in water or environment-friendly solvents (ex. ethanol), as alternative to fullerenes (PC60BM or PC70BM) – the electron-acceptor utilized in most efficient OPVs at present. Fullerenes present serious drawbacks to OPV technology progress: high cost, low contribution to photo-absorption and charge generation, aggregates formation leading to morphological instabilities, low photostability, poor solubility.

We also aim at preparing the electron-donor as analogous to known materials of good performance in cells, but with modified solubility.

We will use molecular design-assisted synthesis to preview their relevant optical properties (absorption spectrum) and frontier energy levels. The molecular structures design also envisages to enhance the devices operation lifetime, since due to being crosslinkable, the new materials may form morphologically stable networks which will be positively reflected on cells lifetimes.

The development of optimal «ink» formulation will comprise the study of the assembly at a nanoscale level of the new materials into favorable (highly absorbing/highly charge generating and transport) film morphologies. We will investigate their photophysical and electric properties relevant for device operation and ultimately, cells laboratory prototypes integrating the new materials will be fabricated and characterized.
Reference:
Funding:
Start Date: 01-04-2016
End Date: 01-03-2018
Team: Ana Maria de Matos Charas, Jorge Manuel Ferreira Morgado, Quirina Alexandra Tavares Ferreira, Cristiana Isabel Violante da Costa, Luís Joaquim Alcácer
Groups: Organic Electronics – Lx
Partners:
Local Coordinator: Ana Maria de Matos Charas
Associated Publications