Abstract
Bright and color-pure electroluminescent materials are of great commercial interest for advanced lighting and display technology. The emergence of metal halide perovskites has given rise to full coverage of the recommendation 2020 standard, the newly defined color gamut in next-generation displays. Despite the recent development of perovskite-based red and green light-emitting diodes (LEDs) that already reach the maximum external quantum efficiency of 20%, it remains challenging to build deep-blue LEDs with comparable device performance. In this Perspective, we review and comment on the synthesis, progress, and challenges toward stable blue electroluminescence (EL), with a focus on (i) anion-exchanged, (ii) quantum-confined colloidal, and (iii) quasi-two-dimensional perovskites. A perspective outlook discussing the strategies of reducing the non-radiative losses and device interface engineering is given at the end.
Highlights
Since the first demonstration of room-temperature electroluminescence (EL) using lead halide perovskites (LHPs),[1] their lightemitting diodes (LEDs) have generated considerable research efforts due to their outstanding characteristics, including solution processability, high color purity, and tunable bandgap.[2,3,4,5,6,7,8] As the blue primary emission component plays an important role in determining the chromaticity and the color rendering index (CRI) of a white light source or display, the development of light-emitting diodes (LEDs), including GaN and organic LED (OLED) technologies, is mainly driven by the performance of deep-blue EL
We have outlined the importance of blue electroluminescence and reviewed the performance of blue-emitting perovskite LEDs based on bulk films, quasi-2D films, bulk colloidal NCs, and NPLs
The performance of blue LEDs based on mixed-anion bulk LHP films and colloidal NCs are typically lower than those of quasi-2D devices because of the intrinsically low EB, thereby resulting in long carrier diffusion lengths and lifetimes
Summary
Since the first demonstration of room-temperature electroluminescence (EL) using lead halide perovskites (LHPs),[1] their lightemitting diodes (LEDs) have generated considerable research efforts due to their outstanding characteristics, including solution processability, high color purity, and tunable bandgap.[2,3,4,5,6,7,8] As the blue primary emission component plays an important role in determining the chromaticity and the color rendering index (CRI) of a white light source or display, the development of LEDs, including GaN and organic LED (OLED) technologies, is mainly driven by the performance of deep-blue EL. Other strategies based on quantum[28,29] and dielectric confinement[30,31,32] that directly increase EB and Eg have yielded high-efficiency blue emitters This perspective is aimed to summarize the recent development and progress of blue perovskite emitters for LEDs, together with discussions about future challenges and perspective in this field.
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