Seeded growth of three-dimensional block heterojunctions featuring heterogeneous long-range exciton migration

Abstract Three-dimensional (3D) block heterojunctions composed of different individual blocks may bring forth emergent properties beyond that of one-dimensional and two-dimensional block heterojunctions. However, the strategies to construct 3D block heterojunctions still lack. Here, we report a living self-assembly of sized-controlled 3D block heterojunctions that show remarkable heterogeneous long-range exciton migration. A near-infrared (NIR) donor–acceptor (D–A) molecule is designed and assembled into a unique 3D architecture as the hetero-seed. The resulting hetero-seed can guide the continuous growth of another D–A molecule in the same fashion to produce the 3D block heterojunction. The seed-guided molecular packing within the outer block is unstable under ultraviolet (UV) irradiation; the photoinduced rearrangement can cause interfacial debonding of the 3D block heterojunction and thereby interrupt the efficient energy transfer from the outer block to the seed core, leading to prominent photoinduced emission enhancement. This phenomenon inspires us to apply the 3D block heterojunction as the platform to precisely measure heterogeneous long-range exciton migration, a valuable parameter for optoelectronic devices whose determination remains a great challenge for organic materials.