Emerging multi-functional delafossite materials: frontier advances and prospective breakthroughs in photoelectronic applications

ABO₂-type delafossites, distinguished by their layered crystalline framework, tunable quantum-enabled properties, and inherent sustainability, represent an emerging multifunctional material platform for next-generation photoelectronics. This review summarizes the frontier advances in delafossite materials science, establishing comprehensive correlations between the fundamental mechanisms and integrated applications of delafossites. The material system exhibits four unique advantages: structural versatility enabling precise composition-structure-property tailoring, exploitable quantum phenomena (ultrahigh conductivity, multiferroicity, and topological states) unlocking unprecedented functionalities, cross-scale functional integration across photoelectronic technology chains, and earth-abundant eco-compatibility aligning with global sustainability goals. Systematic examination encompasses full-spectrum applications-from foundational components (transparent electrodes and charge transport layers) and energy conversion systems (photovoltaics and solar fuels) to high-performance photodetectors, flexible electronics, and quantum photonic devices. Critical breakthrough strategies, including advanced material engineering (defect/interface control and entropy stabilization), computation-accelerated discovery of multinary systems, and quantum-bulk synergy via external-field coupling, are analyzed. Finally, key research gaps are identified with a proposed co-design roadmap integrating quantum mechanisms, non-equilibrium synthesis, and extreme-environment applications to accelerate the translation of delafossites from laboratory innovation to industrial photoelectronic ecosystems.