Interfacial Crystallization‐Driven Assembly of Conjugated Polymers/Quantum Dots into Coaxial Hybrid Nanowires: Elucidation of Conjugated Polymer Arrangements by Electron Tomography

Abstract

A simple and practical “solution‐biphase method” allows the preparation of efficient charge‐transporting 1D nanocrystals with coaxial p–n junctions. It involves gradual diffusion of a top layer of poor solvent (acetonitrile) into a bottom layer of poly(3‐hexyl thiophene)‐b‐poly(2‐vinyl pyridine) (P3HT‐b‐P2VP) conjugated polymers (CPs) and CdSe quantum dots (QDs) dissolved in chloroform. Initial interfacial crystallization‐driven assembly of CPs results in the formation of seeds consisting of dimeric QDs transversely bridged by CPs. Coaxial CPs/QDs hybrid NWs are generated by 1D growth of QDs‐dimeric seeds, enabling tracing of the CPs‐crystallization process via the QDs. Thus, well‐arranged QDs along the longitudinal axis of the NWs infer highly crystalline CPs with edge‐on orientation, as confirmed by electron tomography, UV–vis spectroscopy, and grazing‐incidence wide‐angle X‐ray scattering. This high cristallinity as well as the increased length of the resulting hybrid NWs in solution and the corresponding crystallite size in as‐cast film represent a significant improvement compared to the conventional “one‐pot addition method”. Moreover, although randomly QDs‐attached hybrids of P3HT homopolymer are produced by the solution‐biphase method, branched aggregates with micrometer‐long NW arms are generated from the crystal seeds containing multiple growth facets without precipitate, despite acetonitrile being a nonsolvent.