Photon upconversion, a nonlinear process converting near-infrared light into visible emission, has attracted growing interest for photovoltaics, bioimaging, sensing, and photonic devices. Conventional lanthanide-doped nanomaterials have enabled this field, yet their low-quantum yields and high excitation thresholds limit their applicability. Recent strategies such as core–shell designs, plasmonic coupling, and hybrid composites have significantly enhanced efficiency by suppressing surface quenching and amplifying local electromagnetic fields. Emerging materials, including perovskite quantum dots, carbon quantum dots, and metal–organic frameworks, offer tunable bandgaps, high photostability, and versatile energy transfer pathways, particularly for triplet–triplet annihilation. Complementary theoretical models using rate equations, density functional theory, and Monte Carlo simulations provide insights into dopant optimization and nonradiative losses, accelerating material design. Despite these advances, scalable fabrication, reproducibility, and mitigation of photothermal losses remain key challenges. This review outlines progress in next-generation PUC nanomaterials, bridging experimental and computational approaches to realize efficient, stable, and multifunctional systems for next-generation energy and biomedical technologies.
Keerthana et al. (Fri,) studied this question.