Mechanistic insights into charge transfer engineering in CdSe-based quantum dot-sensitized solar cells

Charge transfer fundamentally determines the photovoltaic efficiency of CdSe-based quantum dot-sensitized solar cells by governing exciton dissociation, carrier transport, interfacial electron injection, and charge recombination. This review develops a mechanism-oriented perspective that correlates the structural, electronic, and interfacial characteristics of CdSe QDs with the charge-transfer processes underlying device operation. The influence of quantum confinement, surface chemistry, defect states, and energy-level alignment is systematically analyzed to establish the intrinsic relationships between material properties and carrier dynamics. Recent advances in interfacial engineering, ligand regulation, heterostructure design, and electronic-state modulation are examined through their mechanistic roles in controlling charge separation, transport kinetics, and recombination pathways rather than solely their impact on photovoltaic performance. Emerging characterization techniques, multiscale theoretical approaches, and data-driven design strategies are further discussed for their potential to enable predictive optimization of charge-transfer behavior. By integrating fundamental charge-transfer physics with rational engineering principles, a unified conceptual framework is presented to guide the rational design of highly efficient, stable, and scalable CdSe-based QD-sensitized solar cells and to identify promising directions for future photovoltaic materials and device development.