Boosting the performance of dye-sensitized solar cells with an ultra-thin passivation layer of star-shaped block copolymer

Herein, a 3-arm star-shaped polystyrene-b-poly(methyl methacrylate) block copolymer (BCP) was synthesized via atom-transfer radical polymerization. This BCP was spin-coated on organic dye-sensitized TiO₂-photoanode to suppress the charge recombination at the electrode/electrolyte interface and enhance the performance of dye-sensitized solar cells (DSSCs). The introduction of an ultra-thin layer of star-shaped block copolymer on the SGT-160 organic dye-sensitized TiO₂ film significantly increased the recombination resistance-nearly doubling it. This improvement led to higher open-circuit voltage and fill factor for the device, thus boosting its performance under simulated one-sun conditions. The enhanced performance can be attributed to several factors: the differing solubility of the two block units in acetonitrile, the presence of ester and phenyl functional groups, and the star-shaped polymer structure, which is well-suited for use as a passivation layer in dye-sensitized solar cells. This structure effectively prevents undesirable back charge transfer while allowing minimal hindrance to the migration of redox species needed for dye regeneration.