High-Luminance Microsized CH₃NH₃PbBr₃ Single-Crystal-Based Light-Emitting Diodes via a Facile Liquid-Insulator Bridging Route

Abstract

Micro-/nanosized organic–inorganic hybrid perovskite single crystals (SCs) with appropriate thickness and high crystallinity are promising candidates for high-performance electroluminescent (EL) devices. However, their small lateral size poses a great challenge for efficient device construction and performance optimization, causing perovskite SC-based light-emitting diodes (PSC-LEDs) to demonstrate poor EL performance. Here, we develop a facile liquid-insulator bridging (LIB) strategy to fabricate high-luminance PSC-LEDs based on single-crystalline CH3NH3PbBr3 microflakes. By introducing a blade-coated poly­(methyl methacrylate) (PMMA) insulating layer to effectively overcome the problems of leakage current and possible short circuits between electrodes, we achieve the reliable fabrication of PSC-LEDs. The LIB method also allows us to systematically boost the device performance through crystal growth regulation and device architecture optimization. Consequently, we realize the best CH3NH3PbBr3 microflake-based PSC-LED with an ultrahigh luminance of 136100 cd m–2 and a half-lifetime of 88.2 min at an initial luminance of ∼1100 cd m–2, which is among the highest for organic–inorganic hybrid perovskite LEDs reported to date. Moreover, we observe the strong polarized edge emission of the microflake-based PSC-LEDs with a high degree of polarization up to 0.69. Our work offers a viable approach for the development of high-performance perovskite SC-based EL devices.

Surface Defect Suppression for High Color Purity Light‐Emitting Diode of Free‐Standing Single‐Crystal Perovskite Film

“…If there is no PMMA treatment, FWHM of 20.4 nm coincides with previous reports of SCPF-based LED (Figure 5c). [19][20][21][22][23] There is a similar tendency of the FWHM for PL spectra. The FWHM of PL decreases from 18.5 to 15.5 nm (Figure S11, Supporting Information).…”

“…[23] As it is well known, the brightness is strongly related to the film thickness and the applied voltage. [25] CH 3 NH 3 Br 3 single-crystal light emitter is thicker (>1 µm), and the applied voltage is higher (9.0 V) than our thickness of ≈200 nm and the applied voltage of 4.0 V. [23] With the similarly applied voltage (≈4 V), the previous brightness has been reported to be 3000 and 3500 cd m −2 , respectively. [24,33] Besides, the brightness requirement of PeLEDs for commercial use is 1000 cd m -2 .…”

“…[22] Single-crystal CH 3 NH 3 PbBr 3 -based LED is manufactured by a liquid-insulator bridging route, getting a narrow FWHM of 20 nm. [23] Moreover, the functional carrier-transport layers cannot be integrated into single-crystal perovskite LED devices, largely limiting the performance of single-crystal PeLEDs. [24,25] Due to low defect concentration, single-crystal perovskite tends to show higher color purity as a light emitter.…”

Hybrid Lead Bromide Perovskite Single Crystals Coupled with a Zinc(II) Complex for White Light Emission

“…Metal halide perovskite single crystals (MHPSCs) provide an imperative choice for photovoltaics and optoelectronic devices with higher efficacy. − The higher carrier mobility, ultralow trap density, long-range order in the crystal lattice, longer carrier diffusion length, fewer grain boundaries and enhanced thermal, moisture and light stability of MHPSCs make them advantageous and preferable optical materials toward fabricating new optoelectronic devices in comparison to their polycrystalline forms. − The optical characteristics such as high quantum efficiency, composition tunable optical band gap, broad absorption spectrum, narrow emission spectrum, high molar absorption coefficient and high power conversion efficiency of MHPSCs are superior to those of their polycrystalline counterparts. These are the central motives of attention for their utilization in research areas ranging from solar cells and photovoltaics to light emitting devices (LEDs) and high-energy radiation detectors applications. − In other words, MHPSCs differ significantly from their polycrystalline properties including the morphology and optical properties and thus are applicable for the improvement of high-performance and stable optoelectronic devices such as solar cells, LEDs, high-energy radiation detectors and flexible electronic devices. − Among the MHPSCs family, hybrid lead bromide perovskites SCs (HLBPSCs) have demonstrated their utility ranging from solar cells to light emitting materials. − For example, the easy solution-based synthesis, high crystalline eminence and substantial stability of HLBPSCs, especially methylammonium lead bromide (CH 3 NH 3 PbBr 3 = MAPbBr 3 ), have demonstrated their practical use in fabricating radiation detectors, photodetectors and solar cells with higher performance and longevity. − In addition, HLBPSCs showed their use in fabricating highly stable and efficient single color emitting LEDs. − However, the optoelectronic applications of HLBPSCs are less widely studied especially for the fabrication of newer white light emitting (WLE) materials. Therefor...…”

Template-Assisted Synthesis of a Large-Area Ordered Perovskite Nanowire Array for a High-Performance Photodetector

“…Organic–inorganic hybrid perovskites (OIHP) have exhibited attractive optoelectronic performance due to their high optical absorption coefficient, long carrier lifetime, and large diffusion length. − One-dimensional NWs are promising building blocks for future nanoscale electronic/optoelectronic devices including photodetectors, transistors, memories, photovoltaics, and solar cells. − Compared to two-dimensional or three-dimensional structures, one-dimensional NWs represent a smaller dimension for transporting carriers, which can always possess lower carrier-scattering probability, longer carrier lifetime, and higher mobility . Besides, polarization-dependent light detection is an important function when detectors are fabricated with NWs. − Therefore, OIHP NWs have caught wide attention and show promising potential applications in optoelectronic devices. , …”