Embodiment of Light-Mediated Main-Chain Scissionable Functionality While Preserving the Structure of Conventional Photoimaging Copolymer

The rational design and development of a main-chain scissionable functional copolymer platform is reported by incorporating a photocleavable nitrobenzyl ester group into the middle of the copolymer backbone while fully preserving its overall structure and function for photopatterning applications on delicate organic semiconductor films. As a model system, a positive-tone photoimaging fluoroalkyl copolymer is used containing a photoisomerizable spiropyranyl unit. The nitrobenzyl ester functionality degrades under UV light and enhances solubility modulation and photopatternability by reducing chain length. This behavior is systematically studied across copolymers with varying, yet narrowly distributed, molecular weights. To further improve the sensitivity of the photoimaging copolymer, it is demonstrated that minimal structural modification of the cleavable group, specifically altering the positions of the methoxy and nitro groups, are highly effective. Finally, a square array of a chemically susceptible organic electron transport material, suitable for organic light-emitting diodes (OLEDs), is fabricated using the copolymer through conventional lithography and pattern transfer processes. This work highlights the importance of rationally designing main-chain scission-type light-sensitive materials that maintain the core structure of conventional materials, making them highly compatible and desirable for standard organic electronic device fabrication processes.