Chemical passivation via functional additives plays a critical role in achieving high performance perovskite light‐emitting diodes (PeLEDs). Here, perovskite composite films for high performance PeLEDs by using zwitterion 3‐aminopropanesulfonic acid (APS) as the additive are developed. The sulfonic group of APS can simultaneously passivate deep and shallow level defects in perovskites via coordinate and hydrogen bonding, which leads to suppressed non‐radiative recombination and ion migration in the perovskite composite films. Based on this, PeLEDs with a peak external quantum efficiency of 19.2% and a half‐lifetime of 43 h at a constant current density of 100 mA cm−2 are obtained, representing one of the most stable and efficient PeLEDs under high current densities.
Quasi‐2D perovskites have shown great potential in achieving solution‐processed electrically pumped laser diodes due to their multiple‐quantum‐well structure, which induces a carrier cascade process that can significantly enhance population inversion. However, continuous‐wave (CW) optically pumped lasing has yet to be achieved with near‐infrared (NIR) quasi‐2D perovskites due to the challenges in obtaining high‐quality quasi‐2D films with suitable phase distribution and morphology. This study regulates the crystallization of a NIR quasi‐2D perovskite ((NMA)2FAn−1PbnI3n+1) using an 18‐crown‐6 additive, resulting in a compact and smooth film with a largely improved carrier cascade efficiency. The amplified spontaneous emission threshold of the film is reduced from 47.2 to 35.9 µJ cm−2. Furthermore, by combining the film with a high‐quality distributed feedback grating, this study successfully realizes a CW NIR laser of 809 nm at 110 K, with a high Q‐factor of 4794 and a low threshold of 911.6 W cm−2. These findings provide an important foundation for achieving electrically pumped laser diodes based on the unique quasi‐2D perovskites.
Realization of electrically pumped laser diodes based on solution‐processed semiconductors is a long‐standing challenge. Metal halide perovskites have shown great potential toward this goal due to the excellent optoelectronic properties. Continuous‐wave (CW) optically pumped lasing in a real electroluminescent device represents a key step to the current injection laser diode, but it has not been realized yet. This is mainly due to the challenge of incorporating a resonant cavity into an efficient light‐emitting diode (LED) which can sustain intensive carrier injection. Here we report CW lasing in an efficient perovskite LED with an integrated distributed feedback resonator, which shows a low lasing threshold of 220 W·cm−2 at 110 K. Importantly, the LED works well at a current density of 330 A·cm−2, indicating the carrier injection rate already exceeds the threshold of optically‐pumping. Our results suggest that electrically pumped perovskite laser diodes can be achieved once the Joule heating issue is overcome.This article is protected by copyright. All rights reserved
Bright and efficient deep‐red light‐emitting diodes (LEDs) are important for applications in medical therapy and biological imaging due to the high penetration of deep‐red photons into human tissues. Metal‐halide perovskites have potential to achieve bright and efficient electroluminescence due to their favorable optoelectronic properties. However, efficient and bright perovskite‐based deep‐red LEDs have not been achieved yet, due to either Auger recombination in low‐dimensional perovskites or trap‐assisted nonradiative recombination in 3D perovskites. Here, a lateral Cs4PbI6/FAxCs1−xPbI3 (0D/3D) heterostructure that can enable efficient deep‐red perovskite LEDs at very high brightness is demonstrated. The Cs4PbI6 can facilitate the growth of low‐defect FAxCs1−xPbI3, and act as low‐refractive‐index grids, which can simultaneously reduce nonradiative recombination and enhance light extraction. This device reaches a peak external quantum efficiency of 21.0% at a photon flux of 1.75 × 1021 m−2 s−1, which is almost two orders of magnitude higher than that of reported high‐efficiency deep‐red perovskite LEDs. Theses LEDs are suitable for pulse oximeters, showing an error <2% of blood oxygen saturation compared with commercial oximeters.
Cesium copper halides have the advantages of high photoluminescence quantum efficiency and good stability, making them attractive for replacing toxic lead halides in the field of perovskite light-emitting diodes (LEDs). However, due to their shallow conduction band and the lack of electron transport layers compatible with it, it remains a great challenge to achieve charge balance in LED devices. This drawback manifests as the accumulation of holes at the interface between the emitting layer and electron transport layer, resulting in nonradiative recombination. Here, we demonstrate an effective approach to address this issue by suppressing hole injection, which is realized through modification of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) layer with polyethylenimine. This leads to cesium−copper−halide LEDs with a high external quantum efficiency of 5.6%, representing an advance in device architecture for efficient electroluminescence from cesium copper halides.
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