High Efficiency Near‐Infrared Perovskite Light Emitting Diodes With Reduced Rolling‐Off by Surface Post‐Treatment

Abstract

The rolling‐off phenomenon of device efficiency at high current density caused by quenching of luminescence in perovskite light‐emitting diodes (PeLED) is challenging to be solved. Here, 2‐amino‐5‐iodopyrazine (AIPZ) is dissolved in a mixed solvent of chlorobenzene (CB)/isopropanol (IPA) (7:3 volume ratio) for surface post‐treatment of FAPbI3 perovskite film. The interaction of AIPZ and perovskite surface not only balances the charge injection but also passivates defects to enhance radiative recombination in PeLED. Therefore, the PeLED champion yields peak external quantum efficiency reaching 23.2% at the current density of 45 mA cm−2 with a radiance brightness of 290 W sr−1 m−2. More importantly, the rolling‐off of device efficiency is significantly reduced. The lowest rolling‐off devices can maintain 80% of peak EQE (22.1%) at a high current density of 460 mA cm−2, whereas the control device only retains 25% of the peak EQE value. This work provides an effective strategy to improve performance and reduce the EQE rolling‐off of PeLED for practical application.

Top-Down Exfoliation Process Constructing 2D/3D Heterojunction toward Ultrapure Blue Perovskite Light-Emitting Diodes

“…As we expected, the IPA treated films exhibited a PL spectrum similar to that of the untreated 3D perovskite films (Figure 1b), which is consistent with the results reported in the relevant literature. 18,24,28,29 This indicates that the simple manipulation of solvent posttreatment is not the key factor affecting the bandgap of the 3D perovskite films. In addition, energy-dispersive X-ray spectroscopy (EDS) has been used to analyze the element composition of the released solution by dynamic posttreatment (Figures S2 and S3).…”

Metal Halide Perovskites: Promising Materials for Light-Emitting Diodes

“…A benign interface quality is also essential for efficient PeLEDs, as it can improve band alignment and passivate surface defects and lead to rapid and balanced charge injection, restricted ion migration and nonradiative recombination, as well as ameliorated EQE roll-off and stability of the PeLEDs [81][82][83][84]. Wei et al [17] dropped a phosphine oxide (PO-T2T) additive solution onto perovskites.…”

Metal Halide Perovskite: A Promising Materials for Light Emitting Diodes

“…A benign interface quality is also essential for efficient PeLEDs, it can improve band alignment and passivate surface defects, leading to rapid and balanced charge injection, restrict ion migration and nonradiative recombination, as well as ameliorate EQE roll-off and the stability of PeLEDs [64][65][66][67]. Wei et al [68]dropped a phosphine oxide (PO-T2T) additive solution onto perovskites, the −P=O bond in the additive bonded tightly with undercoordination Pb 2+ by dative bond at both grain boundaries and surface (Figure 3a), besides, PO-T2T also formed a well energetic alignment to accelerated electron transportation between perovskites layer and electron transport layer (Figure 3b).…”