ZnO-Based Electron-Transporting Layers for Perovskite Light-Emitting Diodes: Controlling the Interfacial Reactions

Abstract

Perovskite light-emitting diodes (PeLEDs) provide new opportunities for cost-effective and large-area electroluminescent devices. It is of interest to use ZnO-based electron-transport layers (ETLs), which demonstrate superior performance in other solution-processed LEDs, in PeLEDs. However, the notorious deprotonation reaction between ZnO and perovskite casts doubt on the long-term stability of PeLEDs with ZnO-based ETLs. This Perspective presents an overview of the chemical reactions that may occur at the interfaces between perovskite and ZnObased ETLs. We highlight that other interfacial reactions during the fabrication of PeLEDs, including the reactions between ZnO and the intermediate phase during perovskite crystallization and the amidation reactions catalyzed by ZnO, demonstrate critical utilities in the fabrication of high-efficiency and stable PeLEDs. Considering these recent advances, we propose future directions and prospects to design and control the interfacial reactions, aiming to fully exploit the potential of ZnO-based ETLs for realizing high-performance PeLEDs.

Metal Halide Perovskites for Red‐Emission Light‐Emitting Diodes

“…[130,131] The disappointed reaction of ZnO is also doubted on the performance of PeLEDs based on the ZnO ETLs. [132] Wang et al introduced [115] Copyright 2020, American Chemical Society. b) Structural phase transitions in black phase of CsPbI 3 versus temperature.…”

“…[ 130,131 ] The disappointed reaction of ZnO is also doubted on the performance of PeLEDs based on the ZnO ETLs. [ 132 ] Wang et al introduced imidazolium (IZ + ) to construct the intermediate state 1D IZPbI 3 perovskite and facilitated the reaction between IZ + and ZnO. This strategy stabilizes the black phase γ‐CsPbI 3 (Figure 8c,d).…”

Influence of ZnO Nanostructure Morphologies on Perovskite Solar Cell Performance: A Review

“…The overall effect is that the chemical stability of ZnO is reduced. The net effect is that electron injection into the oxide is inhibited [61]. ZnO nanostructured materials have also been deployed as photo-anodes in QDSSCs.…”

“…It is now widely accepted that the control of these parameters can be exerted gainfully through the synthesis and device fabrication method. Amongst the most impactful control pathways are the oxide nanostructure and engineering of the interface [56,[58][59][60], the deposition method, posttreatment such as thermal decomposition [60], and doping [61][62][63][67][68][69]. The first reported application of ZnO as an electron transporting layer (ETL) for PSCs was by Kumar et al [70].…”

Revealing a Zinc Oxide/Perovskite Luminescence Quenching Mechanism Targeting Low-Roll-off Light-Emitting Diodes

“…23 In contrast, the overall performance of their visible counterparts with the identical device configuration lags far behind, mainly due to their different perovskite film compositions and crystallization kinetics. 24 The main issue hampering the device performance lies in the vulnerable interfacial contacts between perovskite emitters and ZnO, leading to severe photoluminescence (PL) quenching. 11,25 This detrimental PL quenching phenomenon of perovskite materials on ZnO layers has been widely observed, which was interpreted by the deprotonation of ammonium cations with the assistance of either surface hydroxyl groups or the intrinsic basic nature of ZnO.…”