Hybrid Polymer Films For Solar Cells

By combining the charge-transport properties of conjugated polyelectrolytes and the attractive physical properties of hyperbranched polymers, researchers have made new materials intended for solar cell applications. Kirk S. Schanze, John R. Reynolds, and colleagues at the University of Florida synthesized "hyperbranched conjugated polyelectrolytes," or HB-CPEs, from triphenylamine vinylene and thiophene groups via a reaction based on Heck polycondensation chemistry (J. Am. Chem. Soc. 2007, 129, 8958). The researchers chose these groups to expand the spectrum of visible light absorbed by solar cells. After characterizing the ionic polymers, they fabricated solar cells using HB-CPEs as monolayers and as self-assembled bilayers adsorbed onto titanium dioxide nanoparticles. The greater density of the bilayers resulted in photon-to-electron conversion efficiencies higher than that from monolayers. Performance of the new materials is lower than that of materials in conventional solar cells, the researchers note, but "prospects are high for rapid improvement."