High‐Performance Blue Perovskite Light‐Emitting Diodes Enabled by Efficient Energy Transfer between Coupled Quasi‐2D Perovskite Layers

Abstract

Recently, impressive external quantum efficiencies (EQEs) exceeding 20% are obtained for green, red, and near-infrared perovskitebased LEDs (PeLEDs) through the efforts of perovskite material optimization and device architecture design. [8-10] These achievements firmly prompt the potential applications of PeLEDs in display and illumination fields. However, compared with the efficient PeLEDs, there is only moderate performance reported for blue PeLEDs, [11-18] which undoubtedly restrict PeLED applications in full-color displays and white-light illumination. Thus, the breakthroughs of the device performance are urgently required for blue PeLEDs. Substantial efforts have been made in the past several years to obtain blue perovskite emitters, such as perovskite nanocrystals (NCs), [19-25] 2D perovskite nanoplatelets, [26-32] and quasi-2D perovskites. [33-39] In particular, the quasi-2D perovskites are rising as efficient luminescent materials for highly performed blue PeLEDs due to the cascade energy landscape for efficient exciton transfer and the subsequent radiative recombination. Typically, the quasi-2D perovskites have a formula of B 2 (APbBr 3) n−1 PbBr 4 , While there has been extensive investigation into modulating quasi-2D perovskite compositions in light-emitting diodes (LEDs) for promoting their electroluminescence, very few reports have studied approaches involving enhancement of the energy transfer between quasi-2D perovskite layers of the film, which plays very important role for achieving high-performance perovskite LEDs (PeLEDs). In this work, a bifunctional ligand of 4-(2-aminoethyl)benzoic acid (ABA) cation is strategically introduced into the perovskite to diminish the weak van der Waals gap between individual perovskite layers for promoting coupled quasi-2D perovskite layers. In particular, the strengthened interaction between coupled quasi-2D perovskite layers favors an efficient energy transfer in the perovskite films. The introduced ABA can also simultaneously passivate the perovskite defects by reducing metallic Pb for less nonradiative recombination loss. Benefiting from the advanced properties of ABA incorporated perovskites, highly efficient blue PeLEDs with external quantum efficiency of 10.11% and a very long operational stability of 81.3 min, among the best performing blue quasi-2D PeLEDs, are achieved. Consequently, this work contributes an effective approach for high-performance and stable blue PeLEDs toward practical applications. Metal halide perovskites have emerged as competitive candidates for the next-generation light-emitting diodes (LEDs) due to their excellent optical properties, such as tunable light emission color, high color purity, and high photoluminescence The ORCID identification number(s) for the author(s) of this article can be found under

Advances and Challenges in Two-Dimensional Organic–Inorganic Hybrid Perovskites Toward High-Performance Light-Emitting Diodes

“…4c, d). Moreover, the carrier transfer is completed in picoseconds [77]. Lee et al [43] also observed a similar result, and the enhancement of energy transfer is favorable to reduce the probability of non-radiative recombination, thus improving the device performance.…”

“…Due to the addition of ABA, the interaction between the layers of perovskite was enhanced, and Pb was suppressed to reduce the trapped states and promote the reduction of non-radiative recombination loss. The blue 2D PeLEDs with good performance (EQE = 8.21%) and high stability (T 50 = 81.3 min) were obtained [77]. From the perspective of theoretical calculation, taking n = 2 as an example, the performance of mixed organic cation LEDs is better than that of single spacer cation LEDs, which is attributed to lower formation energy, lower strain and lower electron-phonon coupling [21].…”

“…TA kinetics probed at selected wavelengths (453 and 481 nm) for c pristine and d pristine/ABA perovskite films. Copyright 2020 Wiley-Blackwell[77]…”

High-performance quasi-2D perovskite light-emitting diodes: from materials to devices

“…Judicious phase modulations towards a narrow phase distribution are highly desired to realize pure red and blue emission, which would address the severe optical property degradation in small < n > value films 44 , 115 – 120 . Controlling crystallization by antisolvent techniques or rational large cation spacers and additives can narrow the phase distribution 72 , 115 .…”

Review on Blue Perovskite Light-Emitting Diodes: Recent Advances and Future Prospects

“…The maximum EQE of the sky-blue devices is 12.1%, which is currently the best performance in this field. Ren et al proposed an effective approach to enhance the energy transfer between quasi-2D perovskite layers of the perovskite film for achieving high-performance PLEDs (Ren et al, 2020). They employed a bi-functional ligand of 4-(2-aminoethyl)benzoic acid (ABA) cation into the perovskite film to reduce the weak van der Waals gap between each perovskite layer and to promote the coupling of quasi-2D perovskite layers.…”