Efficient Perovskite Nanograin Light‐Emitting Diodes in Green‐to‐Blue Gamut with Co‐Additive Engineering

Blue perovskite light‐emitting diodes (PeLEDs) have attracted enormous attention; however, their unsatisfactory device efficiency and spectral stability still remain great challenges. Unfavorable low‐dimensional phase distribution and defects with deeper energy levels usually cause energy disorder, substantially limiting the device's performance. Here, an additive‐interface optimization strategy is reported to tackle these issues, thus realizing efficient and spectrally stable blue PeLEDs. A new type of additive‐formamidinium tetrafluorosuccinate (FATFSA) is introduced into the quasi‐2D mixed halide perovskite accompanied by interface engineering, which effectively impedes the formation of undesired low‐dimensional phases with various bandgaps throughout the entire film, thereby boosting energy transfer process for accelerating radiative recombination; this strategy also diminishes the halide vacancies especially chloride‐related defects with deep energy level, thus reducing nonradiative energy loss for efficient radiative recombination. Benefitting from homogenized energy landscape throughout the entire perovskite emitting layer, PeLEDs with spectrally‐stable blue emission (478 nm) and champion external quantum efficiency (EQE) of 21.9% are realized, which represents a record value among this type of PeLEDs in the pure blue region.

Homogenizing Energy Landscape for Efficient and Spectrally Stable Blue Perovskite Light‐Emitting Diodes

Qi,

Tong,

Zhang

et al. 2024

Screening Fluorination Additives for Efficient Perovskite Light‐Emitting Diodes

Xia,

Zou,

Lou

et al. 2024

Fluorinated additives are proposed to address the issue of domain polydispersity in quasi‐2D perovskites. However, the lack of established screening criteria for these additives necessitates a laborious and costly trial‐and‐error process. Herein, this work explores the behind nature for the first time how various fluorination in fluorinated additives affect domain distribution in quasi‐2D perovskites. The studies reveal that fully fluorinated additives could suppress undesirable low‐dimensional domains, facilitating efficient energy transfer, while partially fluorinated additives adversely cause deteriorated optical properties. The observed trend is ascribed to the molecular dipole moment of the fluorinated additives, offering a reasonable explanation for experimental phenomena that has never been reported before. By employing fully fluorinated additives, the fabricated sky‐blue perovskite light‐emitting diodes (PeLEDs) deliver a peak external quantum efficiency (EQE) of 20.38% (@488 nm), marking as one of the highest efficiencies reported to date. The finding provides a screening criterion for fluorinated additives to realize efficient PeLEDs.

Additive‐Driven Enhancement of Crystallization: Strategies and Prospects for Boosting Photoluminescence Quantum Yields in Halide Perovskite Films for Light‐Emitting Diodes

Wang,

Sun,

Shi

et al. 2024

Halide perovskite light‐emitting diodes (PeLEDs) hold great potential for applications in displays and lighting. To enhance the external quantum efficiency (EQE) of PeLEDs, it is crucial to boost the photoluminescence quantum yield (PLQY) of the perovskite films. The use of additives has emerged as a powerful chemical strategy to control the crystallization process in solution‐processed perovskite films. The different types of additives that can be used reflect the various types of chemical interactions with the perovskite materials, influencing their crystallization process in various possible ways. Understanding the relationship between these chemical interactions and their impact on the crystallization process is a key step for designing emitters with improved PLQY and devices with superior EQE. Following the logic chain of additive–perovskite interactions, impacts on crystallization, and subsequent enhancement of PLQY and EQE, this review discusses how additives play a pivotal role in influencing the crystallization process to enhance the PLQY of the perovskite films. Furthermore, this assessment addresses the open challenges and outlines future prospects for the development of PeLEDs.