Toward Stable and Efficient Perovskite Light‐Emitting Diodes

Abstract

Metal halide perovskites (MHPs) are a promising class of materials for next‐generation display and lighting applications. Since the first demonstration of bright electroluminescence (EL) from perovskite light‐emitting diodes (PeLEDs) in 2014, the EQEs of these devices increased from below 1% to more than 20% in merely four years. Despite the meteoritic rise of device efficiencies that placed the new LED technology in the spotlight, many scientific and technical challenges remain, preventing PeLEDs from advancing further into practical applications. The success of inorganic III‐V LEDs, or commercial LED technologies in general, lies in the ability to demonstrate the reliable generation of blue EL. For PeLEDs, high operational stability and efficient blue EL remain to be some of the most pressing goals. To accelerate further developments in these areas, the recent progress in the research of PeLEDs is reviewed. The authors attempt to establish preliminary connections between the degradation mechanisms and the strategies for improvements, exemplified by a selection of recent representative works in the field. Lessons learned from organic LEDs and perovskite solar cells point toward some of the most important directions. This progress report serves as a catalyst for further interdisciplinary research involving materials scientists, chemists, and physicists working together to realize operationally stable PeLEDs.

New Low-Dimensional Lead-Free Perovskite (2-AMP)2BiX7·H2O (X = Cl, Br) Crystals: Synthesis, Stability, and Nonlinear Optical Properties

“…Among them, the rapidly developing solar cells based on the light-absorbing materials organolead halides APbX 3 (where A is an organic cation, X is a halogen anion) have increased the power conversion efficiency more than 20% in merely several years. 10,11 However, the toxicity of lead to the environment and poor stability in the presence of moisture, heat, and extended light exposure have become key bottlenecks toward future commercialization and industrialization. 12 Therefore, there is a great demand to exploit and design hypotoxic lead-free and stable perovskites and their derivatives to replace Pb-based perovskites.…”

High Radiance of Perovskite Light‐Emitting Diodes Enabled by Perovskite Heterojunctions

“…The performance of PeLEDs such as peak EQE, maximum luminance, etc., highly depend on the energy levels and carrier mobilities of the charge transport layers. [ 27 ] The most commonly used HTLs in PeLEDs are semiconducting polymers, with corresponding low hole mobilities in the range of 10 −4 –10 −6 cm 2 V −1 s −1 . [ 8,28–30 ] The low hole mobilities induce the carrier accumulation at the HTL/perovskite interface under a high injection current density, resulting in severe nonradiative recombination, efficiency roll‐off, and a decrease in luminance intensity.…”

Strain coupling and Jahn–Teller effect in efficient and stable sky-blue germanium–lead perovskites

“…Lead-based metal-halide perovskite (MHP) semiconductors demonstrate excellent optoelectronic and luminescent properties, making them ideal key materials for next-generation highefficiency and low-cost optoelectronic devices, [1][2][3][4][5] including solar cells, [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] light-emitting diodes (LEDs), 3,[23][24][25][26][27][28][29] and photodetectors. [30][31][32][33] However, environmental toxicity caused by lead (Pb) severely limits their commercial applications.…”

“…In addition, one of the major challenges for perovskite LEDs is the realization of efficient and stable blue LED devices, which is critical to achieve white-light illumination and full-color displays. 5,[47][48][49] Obtaining stable and efficient blue perovskite films is an important step to finally realize high performance blue perovskite LEDs. Some divalent cations, such as Mn 2+ , Ge 2+ , and Sr 2+ , have been confirmed to effectively improve the efficiency and stability of the perovskite films and LEDs.…”

“…Some divalent cations, such as Mn 2+ , Ge 2+ , and Sr 2+ , have been confirmed to effectively improve the efficiency and stability of the perovskite films and LEDs. 5,36,41,49,50 For example, Hou et al 49 used manganese ions, Mn 2+ , to partially substitute Pb 2+ ions, and it effectively improved the efficiency and spectral stability of the Mn 2+ -doped deep-blue perovskite films. These improvements are due to the reduced density of trap states and enhanced formation energy, respectively, after Mn 2+ substitution.…”