Doped colloidal II-VI quantum wells: advances in synthesis, photophysics and applications.

Doping of colloidal quantum wells (CQWs) has emerged as an effective strategy for tailoring their optical, electronic, and magnetic properties. Incorporation of transition-metal and lanthanide ions can enhance photoluminescence quantum yields (PLQYs), introduce a large Stokes-shifted emission, and tune optical properties across visible and near-infrared (NIR) spectral regions. This review summarizes recent progress in the colloidal synthesis, photophysics, and applications of doped CQWs with a particular focus on Cu-, Ag-, Mn-, Hg-, and Yb-doped CQWs. Their distinct contributions to dopant-mediated emission, magneto-optical and spin-dependent phenomena, and long-wavelength optoelectronics are discussed. The review also examines the use of doped CQWs in light-emitting diodes (LEDs), multiexciton lasing, and Förster resonance energy transfer (FRET). Key challenges include controlling dopant concentration and spatial distribution, identifying dopant sites and oxidation states, clarifying dopant-host interactions, and developing reproducible synthesis and device-integration strategies. Progress in these areas will determine how effectively doped CQWs can be translated into optoelectronic, photonic, and energy-conversion technologies.