Abstract
Ultrafast charge transfer at quantum-dot/metal-oxide (QD-MO) heterojunctions governs the performance ceiling of emerging solar-energy and optoelectronic technologies. This review distills three decades of progress, covering the evolution from classical Marcus theory to modern multi-state, many-body models; the rise of exascale non-adiabatic simulations; and femtosecond spectroscopies that track electron motion in real time. Despite converging evidence for activation-less transfer under strong coupling, direct observation of the Marcus inverted regime remains scarce, largely due to Auger pathways, continuum acceptor states and interfacial defect complexity. We spotlight current strategies-outer-sphere dielectric engineering, single-charge pump-probe designs, and data-driven interface optimization-that are poised to reveal or harness inverted-region kinetics. Looking ahead, integrating low-λ materials, suppressing multi-carrier losses, and uniting operando probes with machine learning could shift QD-MO systems from kinetically limited to thermodynamically dictated performance, inspiring advances in solar fuels, infrared photodetectors and solid-state lighting.