Ultra-Bright Near-Infrared Perovskite Light-Emitting Diodes with Reduced Efficiency Roll-off

Abstract

Herein, an insulating biopolymer is exploited to guide the controlled formation of micro/nano-structure and physical confinement of α-δ mixed phase crystalline grains of formamidinium lead iodide (FAPbI3) perovskite, functioning as charge carrier concentrators and ensuring improved radiative recombination and photoluminescence quantum yield (PLQY). This composite material is used to build highly efficient near-infrared (NIR) FAPbI3 Perovskite light-emitting diodes (PeLEDs) that exhibit a high radiance of 206.7 W/sr*m2, among the highest reported for NIR-PeLEDs, obtained at a very high current density of 1000 mA/cm2, while importantly avoiding the efficiency roll-off effect. In depth photophysical characterization allows to identify the possible role of the biopolymer in i) enhancing the radiative recombination coefficient, improving light extraction by reducing the refractive index, or ii) enhancing the effective optical absorption because of dielectric scattering at the polymer-perovskite interfaces. Our study reveals how the use of insulating matrixes for the growth of perovskites represents a step towards high power applications of PeLEDs.

Thiocyanate-Treated Perovskite-Nanocrystal-Based Light-Emitting Diodes with Insight in Efficiency Roll-Off

“…Furthermore, stable morphology of NC film or stable NC distribution in NC film is expected to be able to relieve efficiency roll-off. This is in agreement with some reports [13,40] on embedding perovskite in a matrix, in which the perovskite NCs or pArticles were fixed in the matrix and morphologies of the films are more stable during operation.…”

Rheological Tunability of Perovskite Precursor Solutions: From Spin Coating to Inkjet Printing Process

“…The intense PL emission band of 10MAPbI 3 -5S peaks at 795 nm, and it is slightly blue, shifting to 790 nm for 5MAPbI 3 -5S. The emission band position and intensities are in line with what was previously reported for these composites, and suggests good optoelectronic properties for the perovskite component of the ink [25].…”

Recent Progress in Emerging Near-Infrared Emitting Materials for Light-Emitting Diode Applications

“…The addition of starch helped the formation of an α-δ mixed phase that can improve the radiative bimolecular recombination and circumvent losses at the interface between the emissive layer and the hole/electron-transporting layer; the improved substrate coverage of the perovskite film can inhibit current leakage and modulate the dielectric landscape, so that the light-outcoupling efficiency can be increased. 160 Many reports have demonstrated that the photophysical properties of perovskite materials can be modulated by changing the halide composition. In 2017, Xiao et al proposed that long-chain ammonium halides can act as surfactants that terminate the grain growth of 3D perovskite in the perovskite solutions during the film-forming process, producing small-grain-sized, ultrasmooth, pinhole-free, and compact perovskite films.…”