Charge injection engineering at organic/inorganic heterointerfaces for high-efficiency and fast-response perovskite light-emitting diodes

Abstract

The development of advanced perovskite emitters has considerably improved the performance of perovskite light-emitting diodes (LEDs). However, the further development of perovskite LEDs requires ideal device electrical properties, which strongly depend on its interfaces. In perovskite LEDs with conventional p-i-n structures, hole injection is generally less efficient than electron injection, causing charge imbalance. Furthermore, the popular hole injection structure of NiOx/poly(9-vinylcarbazole) suffers from several issues, such as weak interfacial adhesion, high interfacial trap density and mismatched energy levels. In this work, we insert a self-assembled monolayer of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid between the NiOx and poly(9-vinylcarbazole) layers to overcome these challenges at the organic/inorganic heterointerfaces by establishing a robust interface, passivating interfacial trap states and aligning the energy levels. We successfully demonstrate blue (emission at 493 nm) and green (emission at 515 nm) devices with external quantum efficiencies of 14.5% and 26.0%, respectively. More importantly, the self-assembled monolayer also gives rise to devices with much faster response speeds by reducing interfacial capacitance and resistance. Our results pave the way for developing more efficient and brighter perovskite LEDs with quick response, widening their potential application scope.

Two-dimensional complex metal halides: influence of restricted dimensionality on functional properties

“…While the highest recorded EQEs for blue LEDs incorporating RP phases remain around 15%, 123,124 green and red LEDs with RP phases have not only reached but, in some cases, even surpassed an impressive EQE of 26%. 92,123,125,126 A deep-red LED with a record efficiency of 26.3% was constructed by introducing large π-conjugated systems capable of suppressing ion migration, improving phase control, reducing defect densities, as well as increasing radiative recombination efficiencies.…”

“…While the highest recorded EQEs for blue LEDs incorporating RP phases remain around 15%, 123,124 green and red LEDs with RP phases have not only reached but, in some cases, even surpassed an impressive EQE of 26%. 92,123,125,126 A deep-red LED with a record efficiency of 26.3% was constructed by introducing large π-conjugated systems capable of suppressing ion migration, improving phase control, reducing defect densities, as well as increasing radiative recombination efficiencies. 92 The cations PPT1 + (2-(5-(3′,5′-dimethyl-[1,1′-biphenyl]-4-yl)thiophen-2-yl)ethyl-1-ammonium) and PPT2 + (2-(5-(2,2′-dimethyl-[1,1′-biphenyl]-4-yl)thiophen-2-yl)ethyl-1-ammonium) were introduced as the A-site in A 2 PbI 4 and displayed significantly improved coverage and stability against ion diffusion than the same A 2 PbI 4 system with A + = BA + and TEA + .…”

Oxygen Vacancy Mediation in SnO2 Electron Transport Layers Enables Efficient, Stable, and Scalable Perovskite Solar Cells

“…Perovskite solar cells (PSCs) have emerged as one of the most promising thin-film solar cell technologies in the photovoltaic field, of which the certified power conversion efficiency (PCE) has rapidly reached an impressive value of 26.1%. , However, due to inherent issues such as ion migration and photothermal decomposition of halide perovskites, the device stability still falls short of meeting the requirements for commercialization. − Conventional PSCs comprise a light-absorbing perovskite layer, an electron-transporting layer (ETL), and a hole-transporting layer (HTL) arranged in a sandwich structure, forming two interfaces. The stability of the perovskite composition and structure at these two interfaces significantly influences the device’s operational lifespan. − Typically, the interfaces of aged devices often feature undesired numerous pinhole structures, primarily attributed to the depletion of organic cations within the perovskite layer. , There are several factors affecting interfacial decomposition, for example, the sublimation loss of the organic cation in the perovskite, primarily due to the weak interfacial binding, particularly at elevated temperatures. − Conversely, decomposition reactions at the contact interface with inorganic metal oxides are closely linked to the catalytic activity of these inorganic materials. , Since it serves as the interface exposed to incident light, the buried interface experiences dual stress from both light and heat. Consequently, the perovskite layer adjacent to this buried interface is more susceptible to degradation, posing a significant challenge to the stability of the devices.…”

Highly Emissive Organic Antimony Halide with Ferromagnetism and Methanol Sensing Properties

“…Organic–inorganic hybrid materials have emerged as a new class of semiconductor materials for electronics, optoelectronics, and photonics. − This type of material contains both organic and inorganic components, and their integration enables the combination of superior electronic, magnetic, optical, thermal, and mechanical properties of inorganic compounds with excellent structural flexibility, processability, light weight, and functionality of organic molecules in the resulting hybrid structures. − Among them, organic metal halides have attracted tremendous attention in the past due to their significant potential as light-emitting materials with structural tunability and impressive emission properties. − The structural diversity of this type of compounds allows scientists to optimize their properties by altering the inorganic and organic components, or the bonding between them, and the overall performance of the hybrids can also be systematically tuned by changing the reactants or reaction conditions. − The structure–property relationships of these structures have been extensively studied in order to obtain high-performance functional materials. , …”