Reducing the impact of Auger recombination in quasi-2D perovskite light-emitting diodes

Abstract

Rapid Auger recombination represents an important challenge faced by quasi-2D perovskites, which induces resulting perovskite light-emitting diodes’ (PeLEDs) efficiency roll-off. In principle, Auger recombination rate is proportional to materials’ exciton binding energy (Eb). Thus, Auger recombination can be suppressed by reducing the corresponding materials’ Eb. Here, a polar molecule, p-fluorophenethylammonium, is employed to generate quasi-2D perovskites with reduced Eb. Recombination kinetics reveal the Auger recombination rate does decrease to one-order-of magnitude lower compared to its PEA+ analogues. After effective passivation, nonradiative recombination is greatly suppressed, which enables resulting films to exhibit outstanding photoluminescence quantum yields in a broad range of excitation density. We herein demonstrate the very efficient PeLEDs with a peak external quantum efficiency of 20.36%. More importantly, devices exhibit a record luminance of 82,480 cd m−2 due to the suppressed efficiency roll-off, which represent one of the brightest visible PeLEDs yet.

Unveiling Crystal Orientation in Quasi‐2D Perovskite Films by In Situ GIWAXS for High‐Performance Photovoltaics

“…To investigate the dynamics of exciton recombination with and without MASCN, the time‐resolved photoluminescence (TRPL) measurements are carried out on glass substrate (Figure 4d) and the decay curves are fitted with biexponential function: Y = A 1 exp(− t /τ 1 ) + A 2 exp(− t /τ 2 ), where short lifetime τ 1 and long lifetime τ 2 manifest trap‐assisted recombination and radiative recombination respectively. [ 36–38 ] Perovskite film with 40% MASCN acquires the τ 1 of 20.16 ns which is much longer than 1.26 ns for the control film, elucidating the reduction of trap density with the addition of MASCN.…”

Promoting Energy Transfer via Manipulation of Crystallization Kinetics of Quasi‐2D Perovskites for Efficient Green Light‐Emitting Diodes

“…[1][2][3][4][5] The external quantum efficiency (EQE) of green and near-infrared perovskite light-emitting diodes (PeLEDs) has exceeded 20%, suggesting their great potential toward commercialization. [6][7][8][9] However, in typical 3D perovskite, the low exciton binding energy and long carrier diffusion length make non-radiative recombination outcompete radiative recombination, especially at low exciting density, limiting the electroluminescence efficiency. [10] Contrary to 3D perovskite, quasi 2D (Q-2D) perovskites feature higher Quasi-2D (Q-2D) perovskites are promising materials applied in light-emitting diodes (LEDs) due to their high exciton binding energy and quantum confinement effects.…”

Two‐dimensional halide perovskite quantum‐well emitters: A critical review

“…To overcome these exciton losses, it is possible to design new polar cationic ligands with weak dielectric confinement to optimize the exciton binding energy (Figure 4A[iii]) in 2D perovskites, which could suppress the exciton‐exciton annihilation and Auger recombination, thereby maintaining radiative recombination at a relatively high rate 75 . Recently, Yuan et al 79 demonstrated the very efficient PeLEDs with a peak EQE of 20.36% and a record luminance of 82 480 cd m −2 by suppressing the Auger recombination. A polar molecule, p ‐fluorophenethylammonium ( p ‐FPEA + ), is employed to generate quasi‐2D perovskites, where the recombination kinetics disclose the Auger recombination rate decreases to one‐order‐of magnitude lower compared to its PEA + analogues, which was attributed to reduced exciton binding energy ( E b ) from p ‐FPEA + .…”