Tribranched Multiblock Copolymers Mimicking the Molecular Claw Design in N-Type Conjugated Polymers for High-Yield Semiconducting Carbon Nanotube Sorting and Phototransistor Memory Applications.

N-type semiconducting polymers are crucial for complementary logic circuits but typically suffer from strong self-aggregation and electronic instability. To address these challenges, a molecular claw architecture for n-type semiconducting tribranched multiblock copolymers is proposed. Two polymers, tAB-1 and tAB-2, are synthesized by incorporating polyisobutylene soft segments into the backbone of a rigid naphthalene-diimide-based semiconducting polymer. The high ratio of soft segments in tAB-2 disrupts backbone planarity and effectively reduces self-aggregation. Consequently, the tAB-2 polymer achieves a sorting purity exceeding 99.9%. Although the polymers have a hyperbranched rather than a well-defined three-arm architecture, this molecular claw-like topology increases the contact area with the nanotube surface. It facilitates the capture of small-diameter carbon nanotubes that possess high intrinsic defect densities. Structural analysis reveals that the composite forms debundled fibers with an increased paracrystalline disorder within the polymer stacks. This loose molecular packing generates abundant charge-trapping sites at the polymer-nanotube heterointerface. Consequently, the tAB-2 phototransistor memory exhibits exceptional electrical characteristics. It achieves a wide memory window of 80 V and a high memory ratio of 105. Furthermore, the device demonstrates stable multibit and dynamic operation at an ultralow drain voltage of -10 mV, with no gate bias, to minimize power consumption. This study confirms that topological engineering effectively balances sorting purity with defect engineering for high-performance organic optoelectronic memory.