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

Abstract

Balanced charge injection is key to achieving perovskite light-emitting diodes (PeLEDs) with a low efficiency roll-off at a high brightness. The use of zinc oxide (ZnO) with a high electron mobility as the charge transport layers is desirable; however, photoluminescence (PL) quenching of a perovskite on ZnO always occurs. Here, a quasitwo-dimensional perovskite on ZnO is explored to uncover the PL quenching mechanism, mainly ascribed to the deprotonation of ammonium cations on the ZnO film in association with the decomposition of low-dimensional perovskite phases. Surprisingly, crystal planedependent PL quenching results indicate that the deprotonation rate strongly correlates with the crystal orientation of the ZnO surface. We developed a strategy for suppressing perovskite PL quenching by incorporating an atomic layer deposited Al 2 O 3 onto the ZnO film. Consequently, an efficient inverted PeLED was achieved with a maximum external quantum efficiency of 17.7% and a less discernible efficiency roll-off at a high current density.

Protocol for efficient and self-healing near-infrared perovskite light-emitting diodes

“…This protocol is also applicable for demonstrating other iodide-based (such as CsPbI 3 , FA x Cs 1-x PbI 3 , and MA x Cs 1-x PbI 3 ( Xu et al., 2021 )) efficient red or near-infrared PeLEDs. However, when bromide- and chloride-based perovskite emitters are selected to fabricate blue and green PeLEDs, severe photoluminescence quenching or perovskite decomposition could be observed, leading to inferior device performance( Bai et al., 2022 ). This is mainly ascribed to bromide- and chloride-based ammonium easily undergo decomposition on the alkaline ZnO/PEIE surface, and the bromide- and chloride-based perovskite crystallize faster than their iodide-based counterparts, both of which could generate amount of defects within the perovskite films.…”

In-Situ Interfacial Reaction Induced Amino-Rich Oxide Surface to Grow High-Quality FAPbBr3 Crystals for Efficient Inverted Light-Emitting Diodes

“…The current density and luminance increase rapidly after a low turn-on voltage of 1.8 V, yielding a maximum luminance of ∼45 600 cd m –2 at 4.8 V. This device demonstrates high EQEs of over 10% in a wide luminance range of 300–25000 cd m –2 and reaches a peak EQE of 12.7% at a luminance of 6500 cd m –2 (Figure d). Notably, the turn-on voltage of 1.8 V is the lowest among all the reported inverted green PeLEDs ,− ,,− (Table S1 in the Supporting Information), which can be contributed by the FAPbBr 3 emissive layer being directly deposited on the ZnMgO ETL. Combining high efficiency and low driving voltage, the highest power efficiency (PE) of our device reaches 36.1 lm W –1 .…”

“…As a result, highly efficient and operationally stable iodine-based PeLEDs with ZnO ETLs have been demonstrated. ,,, The investigation of such interfacial interaction on the bromine-based perovskites remains rare, leaving a challenge to fabricate high-quality green and blue emissive bromine-based perovskites on ZnO ETLs. The current strategy to suppress the interfacial reaction between bromine-based perovskites and ZnO films remains to insert an interlayer, which brings difficulty in thickness control of the interlayer and usually results in higher driving voltages. ,− Demand for better-performed green and blue PeLEDs with ZnO ETLs urgently call for an in-depth understanding of the interaction between bromine-based perovskites and ZnO films.…”

Evolution of Local Structural Motifs in Colloidal Quantum Dot Semiconductor Nanocrystals Leading to Nanofaceting

“…47 It proves that the hydrophilic PbS@TBAI NCs can lead to an efficient charge transfer to ZnO NCs by producing a charge-separated state that decays nonradiatively. 45,46 In Figure 5d, two types of Fermi level (ε f ) alignment between the flat band potential (ε fb ) of ZnO and PbS@TBAI are exhibited. In the open-circuit condition, the Fermi level is offset between the ZnO and S-rich or Pb-rich PbS NCs, which were 270 and 148 meV, respectively.…”

“…The dynamics of the exciton are complex because they include charge transfer and transport within the ZnO interfaces as the presence of the ZnO layer facilitates carrier extraction, which adds another nonradiative pathway that competes with radiative and trap-assisted recombination. 45,46 To quantify and compare the photogenerated charge carrier lifetimes, we fit the TRPL decay with a stretched exponential model to obtain lifetime. 47 The use of this model has been previously suggested to take into account a distribution of monomolecular (e.g., exponential decay) and bimolecular recombination (e.g., biexponential decay) processes, which provide an accepted way of rationalizing complicated exciton dynamics.…”