Recent developments on isoindigo-based conjugated polymers

Isoindigo has recently attracted considerable interest as an electron-deficient building block for conjugated polymers. Polymers based on isoindigo have demonstrated high performances in polymer solar cells (PSC) and in organic field-effect transistor (OFET) devices. The success of isoindigo as a building block results from the combination of several important characteristics such as low-lying frontier orbital energy levels, backbone planarity and extended conjugation, a large local dipole, good solubility after N-alkylation and ease of synthesis in large scale. This mini-review highlights the recent advances in the synthesis of isoindigo related polymers and their applications in PSC and OFET devices.