A Chinese research group has taken a molecular engineering approach to optimize the solubility and thin-film morphology of low-bandgap polymers. They achieved this adjusting the content of pendant groups or side chains on the polymer, in order to enhance the performance of polymer photodetectors.
The group have reported that polymer chains become more ordered with more side chains, and that the morphology of films fabricated with these polymers is also dependent on the side chains. This in turn affects the photocurrent and dark current of photodetectors made from these thin films. A photodetector based on a polymer with 63% side-chain content was found to exhibit high specific detectivity (1.4 × 1012 Jones at 800 nm) and wide spectral response (330-950 nm), among the best reported values for polymer photodetectors and even comparable to that of a silicon photodetector.