Photocaged Perylene Diimide Precursor for Precise Solubility Control and High-Quality Film Fabrication

The inherent contradiction between solubility and electronic properties remains a key challenge limiting the wide application of perylene diimides (PDIs). Here, a novel photocaged precursor strategy is proposed to realize precise solubility transitions by photo-control and to prepare insoluble PDI films directly by irradiating the solution without additional thermal or chemical post-processing. To this end, a specifically designed soluble PDI precursor, N, N'-di-5-(dodecyloxy)-2-nitrobenzyl acetate-3, 4, 9, 10-perylenetetracarboxylic diimide, is synthesized by linking solubilizing chains to the imide-position via photocleavable o-nitrobenzyl (ONB) photocaged group. Upon irradiation at 365 nm, the ONB-linker breaks effectively, removing the solubilizing chains precisely and yielding an insoluble PDI derivative. Spectroscopy results reveal that the photocleavable behavior is effective in both solution and solid states (>76% conversion within 600 s in solution). High-quality insoluble PDI films with favorable flatness and continuity (surface roughness 2.8 nm) and promising conductivity (3.7 × 10^-2 S cm^-1 after chemical doping) are prepared directly in solution by irradiation. This study establishes, for the first time, a universal and spatiotemporally controllable strategy for the direct preparation of insoluble PDI film, offering a new idea for balancing the solubility and charge transport properties, and a potential guideline for solution processing of high-performance, low-solubility organic semiconductors.