Halide perovskite for light-emitting diodes

Perovskite light harvesters (ABX3), as an auspicious light harvester and transforming light energy, have fascinated many communities along with industrialists due to their exceptional properties of the material for solid-state lighting (SSL), flexible, and bandgap tuning thin-film display optoelectronic applications. The perovskite solar cell (PSC) achieved power conversion efficiency (PCE) up to 24%. Furthermore, the external quantum efficiency (EQE) of perovskite light-emitting diodes (LEDs) reached up to 22% recently. So, within a shorter time, perovskite materials have gained marvelous consideration in the past several years. Perovskite-based LEDs are more interesting because of its highly intense PL emission, narrow PL emission spectra, high color purity, low-fabrication cost solution-processed fabrication approaches, and bandgap tunability. For the LEDs applications, most of the bulk (3-D) and nanoparticle/quantum dots (0-D) perovskites forms have been used. In contrast to bulk and single-crystal perovskite LEDs and perovskite quantum dots (PQDs)-based LEDs, the bulk perovskite film-based LEDs demonstrated better performances and higher EQE than PQDs-based thin films. In perovskite quantum dots LEDs, there are ineffective charge-injection and transport because of the loss of many insulating organic ligands into the PQDs. The color gamut from previously reporting high EQE QDs-LEDs was observed up to 140% of the NTSC standard that is nearby the commercial available organic-LEDs optoelectronic devices. On the other hand, several types of research are also going on passive PQD LEDs, which is commonly recognized as a color converter or backlight system that is used for display devices. However, toxicity due to the occurrence of Pb and stability issues of the perovskite material still hinders their commercialization of perovskite LEDs. Considering these problems, many types of researches are going on lead-free and stable perovskite materials nowadays so that stable and efficient perovskite LEDs could be commercialized.