13‐5: Quantum‐Dot‐in‐Perovskite Near‐Infrared Light‐Emitting Diodes

Abstract

Quantum dots represent a unique class of solution‐processed semiconductors with unprecedented optoelectronic properties such as charge transport capability and light absorption/emission. Regarding the latter, the electroluminescence of these nanocrystals can spun a wide wavelength range from the visible to the near infrared through size engineering. However, they exhibit low photoluminescence quantum yield and inferior charge transport properties which hinders their application to light‐emitting diodes. On the other hand, halide perovskite semiconductors exhibit high charge carrier mobility and photoluminescence quantum efficiency approaching unity. However, their emission maxima cannot spun the whole near infrared range due to bandgap induced limitations. Here, we report unique combinations of these classes of semiconductors that allowed the fabrication of efficient near infrared electroluminescent hybrid quantum dot‐in‐perovskite device. In the first approach, core‐shell carbon polymer quantum dots were embedded into the perovskite emissive layer to induce passivation of defect sites and modify the nanomorphology hence resulting to significant efficiency enhancement. In the second approach, silica‐encapsulated silver sulphide quantum dots served as the emissive nanocrystals that were dispersed in a caesium‐containing triple cation perovskite matrix. The latter acted as a highly conductive medium that also offers effective passivation to the emissive nanocrystals. As a result, high external quantum efficiency for a long near infrared wavelength peak electroluminescence was achieved.