Potential and perspectives of halide perovskites in light emitting devices

Abstract

Light emitting diodes (LEDs) have become part of numerous electrical and electronic systems such as lighting, displays, status indicator lamps and wearable electronics. Owing to their excellent optoelectronic properties and deposition via simple solution process, metal halide perovskites possess unique potential for developing halide perovskite-based LEDs (PeLEDs) with superior photoluminescence efficiencies leading to external quantum efficiencies beyond 20% for PeLEDS. However, the limited durability, high operative voltages, and challenges of scale-up are persisting barriers in achieving required technology readiness levels. To build up the existing knowledge and raise the device performance this review provides a state-of-the-art study on the properties, film and device fabrication, efficiency, and stability of PeLEDs. In terms of commercialization, PeLEDs need to overcome materials and device challenges including stability, ion migration, phase segregation, and joule heating, which are discussed in this review. We hope, discussions about the strategies to overcome the stability issues and enhancement the materials intrinsic properties towards development more stable and efficient optoelectronic devices can pave the way for scalability and cost-effective production of PeLEDs.

Keywords: Colloidal perovskite; Device challenges; Electroluminescence; Halide perovskite-based LEDs (PeLEDs); PeLEDs structure; Perovskite nanocrystals; Stability & scalability.

Fig. 1

a Schematic of simple device stacks in n-i-p and p-i-n configuration (b, c) Charge carrier recombination mechanism in perovskite (b) Band diagram showing trap-assisted non-radiative recombination and radiative recombination pathways and (c) the ideal case with radiative recombination only

Fig. 2

Schematic of perovskite materials with different structural dimensionality (Reprinted from Ref. [27] with permission from the Royal Society of Chemistry)

Fig. 3

Possible compositional entropy in organic–inorganic hybrid perovskites and the related improvement in efficiency and stability of PV and PeLED devices

Fig. 4

Band structure and trap states comparison between conventional (III–V or II–VI) semiconductor materials to MAPbI₃ (Reprinted with permission from Ref. [34]. Copyright © 2017 American Chemical Society)

Fig. 5

Schematic illustration of (a) the fs laser-processed perovskite film and the effect of smaller grain size on enhanced radiative recombination [58]. Copyright © 2023, American Chemical Society. b Effect of horizontal and vertical orientations relative to FTO substrate on charge transfer [59]. Copyright ® 2019, American Chemical Society

Fig. 6

a Nucleation and growth mechanism of perovskite layer, b free energy diagram of uniform nucleation. This figure has been published in CCS Chemistry 2022; Droplet Manipulation and Crystallization Regulation in Inkjet-Printed Perovskite Film Formation is available online at 10.31635/ccschem.022.202101583 [65]. Copyright © 2022 Chinese Chemical Society

Fig. 7

Bohr radius and calculated amounts for perovskites

Fig. 8

a Nanocrystal pinning method for perovskite emission property improvement. Reprinted from Ref. [82] Copyright © 2019, Nanoscale. b Schematic representation of the nanocrystal pinning by using anti-solvent during the spin-coating of perovskite inks [43]. © 2017 Elsevier Ltd. All rights reserved

Fig. 9

a Schematic illustration of perovskite deposition techniques. Reprinted from Ref. [52] Copyright © 2021 Energy and Environmental Science. b Vacuum thermal evaporation setup schematic illustration (Reprinted from Ref. [78] Copyright © 2021 The Author(s). Small Science published by Wiley–VCH GmbH)

Fig. 10

Schematic illustrations of a Doctor blade-coating, b slot-die coating, c inkjet printing, d spray coating (Reproduced from Ref. [111] with permission from the Royal Society of Chemistry)

Fig. 11

Energy band diagram for common ETL and HTL in perovskite light emitting diodes (Reprinted from Ref. [154] Copyright © 2016 National Academy of Sciences)

Fig. 12

Defect site driven ion migration in CH₃NH₃PbI₃ (Reprinted from Ref. [162] Copyright © 2015. The Author(s))

Fig. 13

Strategies to reduce ion migration (exemplary). a Energetics of iodide vacancies in 3D MAPbI₃ and 2D PEA₂PbI₄ during different migration paths using DFT calculations. Reprinted from Ref. [182] Copyright © 2017, American Chemical Society. b passivation with alkali cations with the example of KI in a perovskite film Reprinted from Ref. [173]. Copyright © 2018, Macmillan Publishers Limited, part of Springer Nature. All rights reserved. c Working mechanism of grain boundary passivation by organic agent, in this case with TMTA (Reprinted from Ref. [183]. Copyright © 2018, The Author(s))

Fig. 14

a Energetic diagram of ion migration in mixed halide perovskites leading to phase segregation under light irradiation and b bond strength-tolerance factor plot of Pb-X in lead-halide perovskites (Reprinted from Ref. [184]. © 2020 Wiley–VCH GmbH)

Fig. 15

a Joule heating as recorded by a near-infrared camera viewed from ITO/glass surface under bias of 0–6 V and temperature–time plot. Reproduced from Ref. [127] with permission from the Royal Society of Chemistry. b Combination of heat sink with heat spreader as effective countermeasures to thermal degradation (Reproduced from Ref. [193] with permission. Copyright © 2020 WILEY–VCH Verlag GmbH & Co. KGaA, Weinheim)