Synergistic Effect of Dual Ligands on Stable Blue Quasi‐2D Perovskite Light‐Emitting Diodes

Abstract

Since the emergence of inorganic-organic hybrid perovskites a few years ago, there have been many promising achievements in the field of green and red perovskite light-emitting diodes (PeLEDs). Nevertheless, the performance of blue-light PeLEDs faces challenges. In this work, the unique synergy obtained by introducing two different ligands to successfully form quasi-2D perovskite films, which can exhibit stable blue-light emission, is utilized. The fabricated PeLEDs have a maximum external quantum efficiency of 2.62% and a half lifetime (T 50 ) of 8.8 min. Meanwhile, the electroluminescence spectrum with its peak located at 485 nm, demonstrates improved stability by applying different voltage bias. The finding in this work offers a new way to achieve steady blue PeLEDs with high performance.

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

“…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 , where B is an organic spacer cation, A is a monovalent cation (e.g., Cs + , methylammonium (MA + ) or formamidinium, (FA + )), and n represents the number of lead halide octahedral layers.…”

Suppressing Defects‐Induced Nonradiative Recombination for Efficient Perovskite Solar Cells through Green Antisolvent Engineering

“…[39] In Figure 4c,d, a redshift in GSBs for both perovskite films with increasing the delay time is observed which is attributed to high excitation energy transferring to low excitation energy. [40,41] Compared to EthPerovskite, MABrEthPerovskite shows a much slower decay ratio, in which ΔA decrease to 36.2% at 5 ns for Eth Perovskite, while a higher ratio of 51.5% for MABrEthPerovs kite is achieved at same time. In addition, the TA spectrums have red tails extending to 790 and 780 nm for EthPerovskite and MABrEthPerovskite, respectively, which explains corre sponding PL peaks at 792 and 782 nm at molecular dynamic extent.…”

Chelating-agent-assisted control of CsPbBr3 quantum well growth enables stable blue perovskite emitters

“…We employed grazing-incidence wide-angle X-ray scattering (GIWAXS) to probe the orientation of thin films. The interlayer spacing between 2D perovskite layers ( n = 1) is around 17 Å, and the corresponding diffraction peak is at 0.37 Å −1 14 . Diffraction peaks observed at smaller q values are the result of higher ( n = 2 and 3) n domains.…”

“…Extra ligands (e.g., IPABr or PEABr) have been applied to achieve blue emission, but limited control over the distribution of quantum well (QW) widths results in sky-blue emission (longer than 490 nm) and low device performance (EQE below 1.5%). Other strategies in controlling QW thickness also lead to wide n distributions: these films exhibit either redshift of the TA signal wavelength or asymmetric emission peaks 14 , 15 . There is, as a result, significant interest in controlling the QW distribution while keeping photoluminescence quantum yield high.…”