The origins of dual-peak emission and anomalous exciton decay in 2D Sn-based perovskites.

Two-dimensional (2D) Sn-based perovskites exhibit significant potential in diverse optoelectronic applications, such as on-chip lasers and photodetectors. Yet, the underlying mechanism behind the frequently observed dual-peak emission in 2D Sn-based perovskites remains a subject of intense debate, and there is a lack of research on the carrier dynamics in these materials. In this study, we investigate these issues in a representative 2D Sn-based perovskite, namely, PEA2SnI4, through temperature-, excitation intensity-, angle-, and time-dependent photoluminescence studies.

Unraveling the Origin of Long-Lifetime Emission in Low-Dimensional Copper Halides via a Magneto-optical Study.

The origin of the long lifetime of self-trapped exciton emission in low-dimensional copper halides is currently the subject of extensive debate. In this study, we address this issue in a prototypical zero-dimensional copper halide, Cs(C)CuI-DMSO, through magneto-optical studies at low temperatures down to 0.2 K.

Indirect Bandgap Emission of the Metal Halide Perovskite FAPbI at Low Temperatures.

In this work, we provide a picture of the band structure of FAPbI by investigating low-temperature spin-related photophysics. When the temperature is lower than 120 K, two photoluminescence peaks can be observed. The lifetime of the newly emerged low-energy emission is much longer than that of the original high-energy one by two orders of magnitude.

Perovskite Light-Emitting Diodes with Near Unit Internal Quantum Efficiency at Low Temperatures.

Room-temperature-high-efficiency light-emitting diodes based on metal halide perovskite FAPbI are shown to be able to work perfectly at low temperatures. A peak external quantum efficiency (EQE) of 32.8%, corresponding to an internal quantum efficiency of 100%, is achieved at 45 K.

Tin-Based Multiple Quantum Well Perovskites for Light-Emitting Diodes with Improved Stability.

Tin-based halide perovskites have attracted considerable attention for nontoxic perovskite light-emitting diodes (PeLEDs), but the easy oxidation of Sn and nonuniform film morphology cause poor device stability and reproducibility. Herein, we report a facile approach to achieve efficient and stable lead-free PeLEDs by using tin-based perovskite multiple quantum wells (MQWs) for the first time. On the basis of various spectroscopic investigations, we find that the MQW structure not only facilitates the formation of uniform and highly emissive perovskite films but also suppresses the oxidation of Sn cations.

Oriented Quasi-2D Perovskites for High Performance Optoelectronic Devices.

Quasi-2D layered organometal halide perovskites have recently emerged as promising candidates for solar cells, because of their intrinsic stability compared to 3D analogs. However, relatively low power conversion efficiency (PCE) limits the application of 2D layered perovskites in photovoltaics, due to large energy band gap, high exciton binding energy, and poor interlayer charge transport. Here, efficient and water-stable quasi-2D perovskite solar cells with a peak PCE of 18.

Perovskite light-emitting diodes based on spontaneously formed submicrometre-scale structures.

Light-emitting diodes (LEDs), which convert electricity to light, are widely used in modern society-for example, in lighting, flat-panel displays, medical devices and many other situations. Generally, the efficiency of LEDs is limited by nonradiative recombination (whereby charge carriers recombine without releasing photons) and light trapping. In planar LEDs, such as organic LEDs, around 70 to 80 per cent of the light generated from the emitters is trapped in the device, leaving considerable opportunity for improvements in efficiency.

Reduced Efficiency Roll-Off and Enhanced Stability in Perovskite Light-Emitting Diodes with Multiple Quantum Wells.

Mixed-formamidinium (FA) and -cesium (Cs) cations were used to fabricate multiple quantum well (MQW) perovskite light-emitting diodes (PeLEDs). The partial substitution of FA with Cs facilitates the formation of wider quantum wells, which can effectively reduce efficiency roll-off by suppressing Auger recombination. The device has a peak external quantum efficiency (EQE) of 7.

Enhanced Performance of Red Perovskite Light-Emitting Diodes through the Dimensional Tailoring of Perovskite Multiple Quantum Wells.

Halide perovskite multiple quantum wells (MQWs) have recently shown great potential in the field of light-emitting diodes. We report a facile solution-based approach to fabricate dimensionality-tunable perovskite MQWs by introducing 1-naphthylmethylammonium (NMA) cations into CsPbI perovskites. Through the dimensional tailoring of (NMA)CsPbI perovskite MQWs, the crystallinity and photoluminescence quantum efficiencies (PLQEs) are significantly improved.

Efficient Red Perovskite Light-Emitting Diodes Based on Solution-Processed Multiple Quantum Wells.

This paper reports a facile and scalable process to achieve high performance red perovskite light-emitting diodes (LEDs) by introducing inorganic Cs into multiple quantum well (MQW) perovskites. The MQW structure facilitates the formation of cubic CsPbI perovskites at low temperature, enabling the Cs-based QWs to provide pure and stable red electroluminescence. The versatile synthesis of MQW perovskites provides freedom to control the crystallinity and morphology of the emission layer.