Polymer photovoltaics from all-water-solution processing

A green solar cell based on a water-soluble polymer (PTEBS) and water dispersible TiO2 nanocrystals have been developed from all-water-solution processing. The light harvesting ability of water-soluble PTEBS were characterized by the UV-Vis absorption spectroscopy and the morphology of nanocrystalline TiO2 film were characterized by scanning electron microscopy (SEM). The PTEBS/TiO2 photovoltaic devices have showed comparable performance as those from organic-solvent based conjugated polymers (e.g. P3HT, MDMO-PPV, etc.). In addition, due to the very efficient photo-induced charge transfer from conjugated polymers to fullerenes, water soluble fullerenes are also being studied for polymer photovoltaic applications. A negatively charged fullerene derivative is being synthesized and the photovoltaic cells based on PTEBS and water-soluble fullerenes will be studied. By using water as the solvent and utilizing liquid-based processing, the cost of energy generated by this type of solar cell is ultimately expected to approach that of the current fossil fuel. Although the energy conversion efficiencies of these cells are still lower than other solvents based polymer solar cells at the current stage, the concept has shown that photovoltaic cells can be developed from all-water-solution based polymer/nanocrystal (or fullerence) composites and the prospects are high for rapid improvement in efficiencies.