Highly Efficient Preparation of Length and Width-Controllable Donor–Acceptor Nanoribbons via Polymerization-Induced Crystallization-Driven Self-Assembly of Fully Conjugated Block Copolymers

Abstract

Despite the high potential of one-dimensional (1D) donor−acceptor (D−A) coaxial nanostructures in bulk-heterojunction solar cell applications, the preparation of such 1D nanostructures using π-conjugated polymers has remained elusive. Herein, we demonstrate the first example of D−A semiconducting nanoribbons based on fully conjugated block copolymers (BCPs) prepared in a highly efficient procedure with controllable width and length via living crystallization-driven self-assembly (CDSA). Initially, Suzuki−Miyaura catalyst-transfer polymerization was employed to successfully synthesize BCPs containing two types of acceptor shells as the first block, followed by a donor poly(3propylthiophene) core as the second block. The limited solubility and high crystallinity of the core induced a polymerization-induced crystallization-driven self-assembly (PI-CDSA) of the BCPs into nanoribbons during polymerization, providing a tunable width (7.6−39.6 nm) depending on the length of the polymer backbone. Surprisingly, purifying as-synthesized BCPs via simple precipitation directly yielded short and uniform seed structures, greatly shortening the overall protocol by eliminating the timeconsuming process of initial aging and breaking down to the seed required for the conventional CDSA. With this new highly efficient method, we achieved length control over a broad range from 169 to 2210 nm, with high precision (L w /L n < 1.20). Furthermore, combining self-seeding and seeded growth from two different D−A-type BCPs enabled continuous living epitaxial growth from each end of the nanoribbons, resulting in B-A-B triblock D−A semiconducting comicelles with controlled length.