Current device-grade colloidal quantum dot (CQD) inks utilize highly polar solvents, hindering the creation of multilayer devices with varying CQD compositions due to solvent redispersion. This research introduces aromatic ligands to create process-orthogonal CQD inks, enabling the fabrication of multifunctional multilayer CQD structures. The study explores the impact of the ligand's anchoring group on CQD solubility in weakly polar solvents, demonstrating that a carboxyl group induces a dipole enhancing CQD-solvent interactions and enabling colloidal stability without bulky insulating ligands. The resulting ink, used as the hole transport layer in a CQD optoelectronic device, achieved an external quantum efficiency of 84% at 1210 nm.

Seungjin Lee, Min-Jae Choi, Geetu Sharma, Margherita Biondi, Bin Chen, Se-Woong Baek, Amin Morteza Najarian, Maral Vafaie, Joshua Wicks, Laxmi Kishore Sagar, Sjoerd Hoogland, F. Pelayo García de Arquer, Oleksandr Voznyy, Edward H. Sargent