Suppressed Auger Heating of Hot Carriers in Cu‐Doped Colloidal Quantum Wells

ABSTRACT Auger heating represents a major bottleneck for hot carrier (HC) relaxation in colloidal quantum wells (CQWs), delaying carrier accumulation in band‐edge states and diminishing performance in light‐emitting applications. To address this issue, we introduce copper doping in CdSe CQWs to create midgap states, which efficiently suppresses Auger heating without altering their intrinsic structural or optical properties. Ultrafast spectroscopy demonstrates pump‐intensity‐invariant HC cooling dynamics in Cu‐doped CQWs, occurring within ∼0.21 ps at a consistent energy‐loss rate of ∼610 meV/ps, even under high exciton densities ( ≈ 4). In contrast, undoped samples exhibit significant cooling deceleration as excitation intensity increases. Combined experimental and theoretical results attribute this ultrafast cooling to rapid hole trapping at Cu 1 + sites, which disrupts the biexcitonic energy‐transfer mechanism responsible for Auger reheating. This work establishes a practical strategy for achieving rapid carrier cooling essential for high‐performance CdSe CQW‐based optoelectronics.