Positioning Lithium Ions by Host–Guest Chemistry Combined with Self-Assembly Using a Thiophene-Based All-Conjugated Amphiphilic Block Copolymer

Abstract

Self-assembly of poly(3-hexylthiophene) (P3HT) driven by - stacking, combined with Host-Guest Chemistry of ethylene glycol oligomer and lithium ion is demonstrated using a thiophene-based all conjugated amphiphilic block copolymer, containing 93 mol % of P3HT and 7 mol % of poly(3-(2-(2-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-ethyl))thiophene), P3EGT blocks. An ion chelating ability of ethylene glycol oligomers with lithium ions in the P3EGT block is confirmed using H-1-NMR spectrometry. This method could allow positioning lithium ions at the interface between P3HT domains and PC61BM clusters, confirmed using XRD and photoluminescence quenching experiments. The compact lamellar P3HT domains by side repulsion driven self-assembly of amphiphilic block copolymer and the molecular engineering of the interface with an optimized lithium contents are resulted in the improvement of photovoltaic performance in an organic solar cell (2.1-3.0%). (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1068-1074