Recent Advancements in Near-Infrared Perovskite Light-Emitting Diodes

Metal halide perovskites have shown excellent properties for lighting applications, including high photoluminescence quantum yield (PLQY), compositional tunability, and narrow emission line widths. Perovskite light-emitting diodes (LEDs) have achieved external quantum efficiency (EQE) up to 20% in the green, red, and near-infrared (NIR) spectral regions. Recently, nanostructured perovskite NIR-LEDs have displayed 100 h of device stability, making this technology commercially viable and prompting greater awareness of this class of devices, as distinct from visible wavelength perovskite LEDs. Even so, the current generation of high-performance perovskite LEDs are still hampered by slow radiative recombination of charge carriers, unbalanced injection of charge carriers, and light out-coupling efficiency; therefore, more structural and morphological engineering of perovskite LEDs is needed to confine the charge carriers and collect the photons more effectively. It has been observed that 3D bulk perovskites show high performance but have poor stability and offer less control over their optical properties. In contrast, NIR-emitting perovskite nanocrystals offer precise control of their optical properties but exhibit poor optoelectronic properties due to the presence of bulky ligands. Quasi-2D perovskite systems have gained significant attention as they balance high conductivity and stability, while enabling precise color tuning of nanostructures, and the possibility to produce single crystal-LEDs. Here, we assess these and other recent advancements in NIR-emitting perovskite materials. We compare different structural frameworks and how they influence the LED performance in terms of color stability, EQE, and device stability. The practical challenges facing each of these structural classes of perovskite NIR-LED materials and the possible strategies to overcome these obstacles are thoroughly discussed.