Polymeric Squaraine Dyes as Electron Donors in Bulk Heterojunction Solar Cells
Abstract
A polysquaraine low-band-gap polymer was synthesized by Yamamoto coupling of a monomeric dibromoindolenine squaraine dye. The resulting polymer has 
≈ 34 000 and PDI ≈ 1.7. The electronic properties of monomer and polymer were investigated by CV, absorption, and emission spectroscopy. Bulk heterojunction solar cells were prepared from blends of the polysquaraine with the fullerene derivative PCBM in different weight ratios (1:3 to 1:1). The power conversion efficiencies under simulated AM1.5 conditions yielded 0.45% for these non-optimized systems. The EQE shows that the photoresponse spans the range from 300 to 850 nm, which illustrates the promising properties of this novel organic semiconductor as a low band gap donor material in organic photovoltaics.
