RESUMEN
Owing to their excellent optoelectronic properties, quasi-2D perovskites with self-assembled multiple quantum well (MQW) structures have shown great potential in light-emitting diode (LED) applications. Understanding the correlation between the bulky cation, quantum well assembly, and optoelectronic properties of a quasi-2D perovskite is important. Here, we demonstrate that the dipole moment of the bulky cation can be one of the fundamental factors that controls the distribution and crystallinity of different quantum wells. We find that the bulky cation with a moderate dipole moment leads to moderately distributed well-width MQWs, resulting in a superior device efficiency due to the simultaneous achievement of favorable optical and electronic properties. The peak external quantum efficiency and the maximum luminance of the champion device are 10.8% and 19082 cd m-2, respectively, positioning it among the best-performing quasi-2D green perovskite LEDs without further surface passivation or additive doping. This work provides a perspective on the rational design of bulky cations in quasi-2D perovskite LEDs, which is also essential for the development of other mixed-dimensional perovskite optoelectronic devices.
RESUMEN
Tin-based halide perovskites have attracted considerable attention for nontoxic perovskite light-emitting diodes (PeLEDs), but the easy oxidation of Sn2+ 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 Sn2+ cations. The tin-based MQW PeLED exhibits a peak external quantum efficiency of 3% and a high radiance of 40 W sr-1 m-2 with good reproducibility. Significantly, these devices show excellent operational stability with over a 2 h lifetime under a constant current density of 10 mA cm-2, which is comparable to that of lead-based PeLEDs. These results suggest that perovskite MQWs can provide a promising platform for achieving high-performance lead-free PeLEDs.
