The Future of Light-Emitting Materials

L ight-emitting materials have repeatedly transformed modern technology.Fluorescent lamps, phosphorconverted light-emitting diodes (pc-LEDs), organic LEDs (OLEDs), quantum-dot LEDs (QD-LEDs), perovskite LEDs (PeLEDs), and micro-LED displays, each, emerged through advances in materials chemistry that enabled not only higher efficiency but also control over color purity, bandwidth, lifetime, and processability.[1][2][3][4] Today, several classes of emitters routinely achieve high photoluminescence quantum yields, while OLEDs, QD-LEDs, and PeLEDs have reached electroluminescence efficiencies that would have been considered exceptional only a few years ago.[5][6][7][8][9][10] The future of light-emitting materials should not be viewed simply as the parallel advancement of OLEDs, PeLEDs, quantum dots, phosphors, and their applications.Such a classification is useful technologically, but it does not capture the deeper materials' challenges shared by all emitters: how excitation energy is created, redistributed, coupled to the lattice or environment, and ultimately converted into useful photons.High quantum efficiency alone is, therefore, no longer sufficient to define a future-ready emitter.The central challenge is to control the entire pathway from excitation to photon emission under increasingly demanding spectral and operational conditions.The future of light-emitting materials lies in controlling the excited-state behavior across multiple dimensionsfrom emission wavelength and electron-phonon coupling to stability, interfaces, and integrated systems.NIR emission serves as a particularly stringent test of this control because its relatively small energy gaps favor nonradiative loss, making it more difficult to direct excitation energy into useful photons.Figure 1 summarizes this shift from optimizing individual classes of emitters toward engineering the complete excited-state-tophoton pathway.The field is evolving beyond the parallel optimization of individual emitter classes toward control of the complete excited-state-to-photon pathway.Five interconnected dimensions define this emerging landscape: (1) excited-state design; (2) stability and suppression of nonradiative loss; (3) wavelength extension from the visible to NIR-I, NIR-II, and NIR-III through host-phonon and activator engineering; (4) control of interfaces and integration into increasingly complex light-emitting systems; and (5) sustainable, AI-guided exploration of materials' space.NIR emission provides a particularly stringent test because decreasing photon energy increases the competition between radiative emission and phonon-assisted nonradiative relaxation.