Pure-bromide quasi-2D perovskite (PBQ-2DP) promises high-performance light-emitting diodes (LEDs), while a challenge remains on control over its n-phase distribution for bright true-blue emission. Present work addresses the challenge through exploring the passivation molecule of amino acid with reinforced binding energy, which generates narrow n-phase distribution preferentially at n = 3 with true blue emission at 478 nm. Consequently, a peak external quantum efficiency of 5.52% and a record brightness of 512 cd m −2 are achieved on the PBQ-2DP-based true blue PeLED, these both values located among the top in the records of similar devices. We further reveal that the electron−phonon coupling results in the red-shifted emission in the PBQ-2DP film, suggesting that the view of n-phase distribution dominated true-blue emission in PBQ-2DP needs to be revisited, pointing out a guideline of electron−phonon coupling suppression to relieve the strait of realizing true blue or even deep blue emission in the PBQ-2DP film.
The fabrication of blue perovskite light‐emitting diodes (PeLEDs) in air conditions promises to liberate the manipulation procedures from the protection of inert atmosphere in the glovebox, which will remarkably promote the commercialization proceeding of perovskite‐based optoelectronic devices in display applications. However, achieving air‐processed blue PeLEDs in the interference of moisture meets great challenges in crystallization kinetics control. Herein, it is proposed that substrate‐adsorbed moisture dominates the perovskite crystallization kinetics during the fabrication in air, and the limited moisture from nonhygroscopic substrate inhibits the nucleation of the large‐n phase and allows the growth of the small‐n phase, thus yielding blue quasi‐2D perovskite films in a wide moisture range of 10–50% relative humidity. Then, air‐processed blue PeLEDs are successfully achieved for the first time, showing a brightness of 968 cd m−2, external quantum efficiency of 2.54% at stable peak emission of 483 nm, as well as an outstanding operating stability of 546 s at a peak brightness of 45 cd m−2, which are favorably competitive with PeLEDs fabricated in the glovebox. This work provides a guideline for air‐processed blue PeLEDs fabrication, which paves the way for air‐processed PeLEDs in further application of commercialization display.
Metal halide perovskite microwires (MWs) have emerged as promising photoactive materials for highly efficient photodetectors (PDs). However, large-scale MWs film fabrication is still a formidable challenge for achieving integration compatible perovskite PDs arrays, owing to precipitation and structure crushing of MWs during deposition and annealing. Herein, a strategy of fabrication of inch-scale perovskite MWs films is presented by depositing perovskite intermediate suspension through spray-coating, which addresses the trade-off present between the high flatness of MWs film and its large-scale fabrication. The single crystalline perovskite MWs weave a film with high enough flatness rendering narrow performance distribution of high efficiency on the 7 × 7 PDs arrays. The formamidinium lead iodide (FAPbI 3 ) PDs arrays show average responsivity and detectivity of (1.60 ± 0.46) A W −1 and (1.49 ± 0.50) × 10 12 Jones. The methanaminium lead iodide (MAPbI 3 ) PDs arrays show average responsivity and detectivity of (0.065 ± 0.046) A W −1 and (2.54 ± 0.77) × 10 11 Jones. The champion PDs based on FAPbI 3 MWs film and MAPbI 3 MWs film show detectivity of 1.26 × 10 13 and 9.67 × 10 11 Jones, which are much higher than that of corresponding polycrystalline films and located on the top ranking of similar devices.
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