Quantum dots (QDs) are semiconductor nanocrystals with sizes on the order of several nanometers, whose bandgaps can be tuned by controlling the particle size. Owing to this bandgap tunability, QDs can absorb near-infrared (NIR) and short-wave infrared (SWIR) light, spectral regions that are difficult to access with conventional silicon-based devices. However, colloidal QDbased infrared photodetectors still suffer from intrinsically high dark current, trap-induced noise, and limited response speed. As a result, they exhibit fundamental performance gaps in terms of detectivity and speed–bandwidth product compared to epitaxial infrared detectors, highlighting the need for structural and architectural design strategies to overcome these limitations. In this review, we discuss recent advances in enhancing the spectral selectivity and sensitivity of infrared photodetectors through three-dimensional optical architectures, including metasurfaces and metamaterials. We focus in particular on design strategies and the underlying mechanisms responsible for performance enhancement, and we outline how structural approaches can be leveraged to effectively control the sensitivity and wavelength selectivity of QD-based infrared detectors.

Metamaterials, as artificially engineered structures with unconventional mechanical and acoustic properties, have recently emerged as a transformative platform for enhancing the capabilities of triboelectric nanogenerator (TENG) systems. Since the invention of TENG devices, extensive efforts have been devoted to improving charge density, output stability, and overall performance. Conventional performance optimization strategies mainly rely on device-level improvements such as surface chemistry modification, microstructuring, and nanopatterning. However, limited emphasis has been given to system-level development of smart self-powered intelligent systems. The integration of metamaterials into TENG devices opens a new era by enabling frequency-selective localization, mechanical impedance matching, and controllable deformation pathways. These engineered mechanical structures not only improve energy harvesting efficiency but also introduce new functionalities into the system. This review systematically summarizes recent advances in metamaterial-integrated TENG systems across four major application domains: (i) energy harvesting, (ii) acoustic telecommunication and acoustic-to-electric conversion, (iii) self-powered sensing, and (iv) vibration suppression and monitoring. Overall, the integration of metamaterials into TENG systems will pave the way for next-generation sustainable, intelligent, self-powered devices with diverse functionalities.