Highly bright perovskite light-emitting diodes enabled by retarded Auger recombination

Abstract

One of the key advantages of perovskite light-emitting diodes (PeLEDs) is their potential to achieve high performance at much higher current densities compared to conventional solution-processed emitters. However, state-of-the-art PeLEDs have not yet reached this potential, often suffering from severe current-efficiency roll-off under intensive electrical excitations. Here, we demonstrate bright PeLEDs, with a peak radiance of 2409 W sr^-1 m^-2 and negligible current-efficiency roll-off, maintaining high external quantum efficiency over 20% even at current densities as high as 2270 mA cm^-2. This significant improvement is achieved through the incorporation of electron-withdrawing trifluoroacetate anions into three-dimensional perovskite emitters, resulting in retarded Auger recombination due to a decoupled electron-hole wavefunction. Trifluoroacetate anions can additionally alter the crystallization dynamics and inhibit halide migration, facilitating charge injection balance and improving the tolerance of perovskites under high voltages. Our findings shed light on a promising future for perovskite emitters in high-power light-emitting applications, including laser diodes.

Fig. 1. Device structure and performance characteristics of our PeLEDs.

a Device configuration and cross-sectional SEM image of the PeLED. The scale bar represents 100 nm. b Electroluminescence (EL) spectra of the device at different voltages. c Dependence of EQE on the current density (EQE–J). d Dependence of EQE on the radiance (EQE-R). e Dependence of current density and radiance on the voltage (J–V–R). f A comparison of device efficiency and radiance with the state-of-the-art NIR PeLEDs reported in the literatures (Supplementary Table 1). g Stability of the device measured at a high current density of 100 mA cm⁻².

Fig. 2. Carrier recombination dynamics of perovskite films.

TA spectra for (a) F- and (b) FCT-films, respectively. c Power dependent I_PL0 for F- and FCT-films. The I_PL0 values were extracted from TRPL spectra at time zero. d PLQY as a function of excitation power density for F-and FCT-films. Proportion of the recombination ratio as a function of carrier density for the F- (e) and FCT-films (f), respectively. g Derived values of recombination rate constant for the F- and FCT-films, where k₁ was extracted from low-fluence TRPL spectra, and k₂ and k₃ were extracted from both TRPL and TA measurements. The error bars indicate the confidence intervals of the fitted rates.

Fig. 3. Perovskite film characteristics and device electric simulations.

a SEM images of F- and FCT-films. The scale bar represents 1 μm. b, AFM and 3D AFM images of F- and FCT-films. The scale bar represents 1 μm. The electric simulation and simulated electric field profile of devices with low (c) and full coverage (d) perovskite films (the color represents the electric potential gradient distribution inside of the devices). e Simulated holes distribution after carrier injection in PeLEDs at the bias of 6 V. f Dependence of loss ratio on bias and surface coverage.

Fig. 4. Mechanisms of TFA⁻ anions on improving the PeLED performance.

a Core-level spectra of F 1 s and C 1 s obtained from high-resolution XPS of F- and FCT-films. b Lattice structures and corresponding electron cloud density for FAPbI₃, FA_1-xCs_xPbI₃, and FA_1-xCs_xPbI₃ with TFA⁻ adsorption, respectively. The isosurface is 0.1 eV/ų. c ¹H NMR spectra of different materials dissolved in DMSO-d6. The red and grey squares highlight the characteristic peaks of FA⁺. d ATR-FTIR spectroscopy data for CsTFA and CsTFA−PbI₂ samples (with molar ratio of 1:1). e XRD of the F- and FCT-films before thermal annealing. The insert are the photographs of the perovskite films before and after thermal annealing. f Determination of desorption energy (E_d) of the I⁻ on different perovskite surface: With iodide vacancies (I), prefect structures (II), and passivated with TFA⁻ anions. g ToF-SIMS characteristics of F- and FCT-devices before and after electrical aging. Here, the red circle highlights the increased accumulation of I⁻ ions close to the anode for F- devices.