Abstract
Lead halide perovskites have attracted tremendous attention in photovoltaics due to their impressive optoelectronic properties. However, the poor stability of perovskite-based devices remains a bottleneck for further commercial development. Two-dimensional perovskites have great potential in optoelectronic devices, as they are much more stable than their three-dimensional counterparts and rapidly catching up in performance. Herein, we demonstrate high-quality two-dimensional novel perovskite thin films with alternating cations in the interlayer space. This innovative perovskite provides highly stable semiconductor thin films for efficient near-infrared light-emitting diodes (LEDs). Highly efficient LEDs with tunable emission wavelengths from 680 to 770nm along with excellent operational stability are demonstrated by varying the thickness of the interlayer spacer cation. Furthermore, the best-performing device exhibits an external quantum efficiency of 3.4% at a high current density (J)of 249mA/cm2 and remains above 2.5% for a J up to 720mAcm-2, leading to a high radiance of 77.5W/Srm2 when driven at 6V. The same device also shows impressive operational stability, retaining almost 80% of its initial performance after operating at 20mA/cm2 for 350min. This work provides fundamental evidence that this novel alternating interlayer cation 2D perovskite can be a promising and stable photonic emitter.
Highlights
Two-dimensional (2D) metal halide perovskites have recently attracted broad attention due to their impressive optoelectronic properties for various applications [1,2,3], such as solar cells [4, 5], photodetectors [6] and lightemitting diodes (LEDs) [7,8,9]
Devices based on alternating cations in the interlayer space (ACI) retain approximately 80% of their initial performance after operating at 20 mA/cm2 for 350 min, outperforming the operational stability of perovskite LEDs (PeLEDs) fabricated with the same device structure but different perovskites [8, 17, 33]
We first studied the crystal structure of the obtained ACI perovskite films using grazing-incidence X-ray diffraction (GIWAXS) measurements (Figure 1(a–c)) that have been extensively used in recent years to characterize 2D and 3D perovskites [20, 21, 23, 34,35,36,37]
Summary
Two-dimensional (2D) metal halide perovskites have recently attracted broad attention due to their impressive optoelectronic properties for various applications [1,2,3], such as solar cells [4, 5], photodetectors [6] and lightemitting diodes (LEDs) [7,8,9]. Due to the higher binding energy between the layered structures and higher molecular dissociation energy of the DJ structure than that of the RP structure, a significant improvement in operational stability was observed for the devices using the DJ structure This indicates that the chemical and crystal nature of 2D perovskites play a crucial role in determining the performance of PeLEDs. To improve the structural properties of 2D perovskites even further, a novel approach with two different alternating cations in the interlayer space (ACI) has been introduced. Devices based on ACI retain approximately 80% of their initial performance after operating at 20 mA/cm for 350 min, outperforming the operational stability of PeLEDs fabricated with the same device structure but different perovskites [8, 17, 33] This demonstrates the initial promise of ACI perovskites for stable PeLED application
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