2D materials in functional optoelectronics: recent advances and future prospects

Two-dimensional (2D) semiconductors, such as MXenes, transition metal dichalcogenides, black phosphorus, and emerging van der Waals heterostructures, have revolutionized the field of optoelectronics by offering exceptional electrical, optical, and mechanical properties at atomic-scale thickness. Their unique features, including tunable bandgaps, high absorption coefficients, and strong excitonic effects, enable a wide range of light detection and light emission applications, making them key materials for next-generation functional optoelectronic devices. This review explores recent breakthroughs in light detection technologies using 2D materials. As photodetectors, they offer ultrafast response rates and high sensitivity across a broad spectral range. In solar cell applications, 2D materials contribute to the development of lightweight, flexible, and efficient photovoltaic devices with enhanced charge transport. Image sensors based on 2D materials exhibit superior spatial resolution and spectral selectivity, while their integration into biomedical imaging platforms enables non-invasive diagnostics due to their biocompatibility. Furthermore, novel morphable light-tracking devices leverage the mechanical flexibility and photoresponsivity of 2D materials for adaptive photonic systems in wearable and robotic applications. On the emission front, 2D semiconductors are emerging as active light-emitting materials in LEDs, lasers, and quantum emitters, benefiting from direct bandgaps in monolayers and strong quantum confinement effects. Additionally, their application as backplane driving circuits in flexible displays is gaining momentum due to their high mobility, mechanical robustness, and transparency, enabling foldable and stretchable display technologies. Despite these advancements, practical implementation faces persistent intrinsic challenges such as high contact resistance, environmental instability, difficulties in controlled doping, and a lack of scalable, reproducible synthesis methods. These issues hinder device reliability and integration. This review also outlines the perspective toward commercialization, emphasizing the need for advancements in heterostructure engineering, and interface optimization. Through interdisciplinary collaboration and innovative material processing, 2D semiconductors are poised to reshape the landscape of optoelectronics, bridging the gap between fundamental science and practical technologies.