Fabrication of ZnO dual electron transport layer via atomic layer deposition for highly stable and efficient CsPbBr₃ perovskite nanocrystals light-emitting diodes

Abstract

Electron transport layers (ETLs) are important components of high-performance all-inorganic perovskite nanocrystals light-emitting diodes (PNCs-LED). Herein, atomic layer deposition (ALD) of inorganic ZnO layer is combined to the organic 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) to form dual ETLs to enhance both the efficiency and stability of PNCs-LED simultaneously. Optimization of ZnO thickness suggested that 10 cycles ALD yields the best performance of the devices. The external quantum efficiency (EQE) of the device reaches to 7.21% with a low turn-on voltage (2.4 V). Impressively, the dual ETL PNCs-LED realizes maximum T50 lifetime of 761 hours at the initial luminance of 100 nit, which is one of the top lifetimes among PNCs-LEDs up to now. The improved performance of dual ETL PNCs-LED is mainly due to the improved charge transport balance with favorable energy level matching. These findings present a promising strategy to modify the function layer via ALD to achieve both highly efficient and stable PNCs-LED.

Atomic layer deposition in advanced display technologies: from photoluminescence to encapsulation

“…As a result, the external quantum efficiency (EQE) of the device was improved significantly due to the enhanced charge transport balance with favorable energy level matching [46]. Moreover, the T 50 lifetime of the device was increased to 761 h at the initial luminance of 100 nit, which is one of the highest lifetimes reported to date for PQLEDs [34]. In another study, a NiO x film was deposited on poly(ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS) to fabricate an inorganic/organic dual hole injection layer (HIL, bottom inset, figure 4(b)) [29].…”

“…Copyright (2021) American Chemical Society. Reproduced from [34]. © IOP Publishing Ltd All rights reserved.…”

“…Thus, figure 4(b) outlines the process employed to construct ETLs and HTLs via ALD based on a well-controlled thickness. More specifically, a layer of zinc oxide layer is deposited onto 1,3,5-tris(1phenyl-1H-benzimidazol-2-yl)benzene via ALD at low temperatures to form inorganic/organic dual ETLs in the device structure (top inset, figure 4(b)) [34]. As a result, the external quantum efficiency (EQE) of the device was improved significantly due to the enhanced charge transport balance with favorable energy level matching [46].…”

“…Upon the use of ALD to introduce an ITO barrier layer in advanced displays, ion diffusion from the ITO layer was effectively blocked, mitigating device degradation and enhancing its long-term stability [26,51]. Additionally, ALD enables efficient exciton confinement during dual-ETL fabrication [34], ultimately enhancing the display performance and efficiency.…”

“…Thus, following suitable modification of the functional layers, an excellent transport balance between the electrons and holes can be achieved. Moreover, the introduced ALD layers can also act as barriers to confine excitons and improve radiative recombination in the EML [34].…”