Chloride ions kill the stability of blue perovskite light emitting diodes

Chloride ions kill the stability of blue perovskite light emitting diodes
by Simon Mansfield
Sydney, Australia (SPX) Nov 30, 2023

In the dynamic world of light-emitting diode (LED) technology, blue perovskite light-emitting diodes (PeLEDs) have emerged as a focal point of research, given their significant role in modern lighting and display technology. These innovative devices, akin to established technologies such as III-V, organic, and quantum dot LEDs, have been the subject of intense study due to their potential for high efficiency and vivid color rendering. However, a persistent challenge in the development of blue PeLEDs has been achieving operational stability, a hurdle that continues to impede their commercial viability.

Recent years have witnessed a notable surge in the external quantum yields of blue PeLEDs, edging them closer to the performance levels of more mature LED technologies. Despite these advancements, blue PeLEDs face a critical limitation: their operational stability remains alarmingly low. Even under relatively moderate conditions, their half-lifetime is disappointingly brief, ranging from just tens of seconds to a few minutes. This short lifespan poses a significant barrier to their practical application in industries reliant on long-lasting and reliable lighting solutions.

Addressing this challenge, a collaborative research effort led by Prof. Weidong Xu from Northwestern Polytechnical University in China and Prof. Feng Gao at Linkoping University in Sweden has shed light on the root cause of this instability. The team's investigation focused on mixed chloride/bromide perovskites, commonly used to achieve the desired blue emission in PeLEDs.

Their findings, published in the journal "Frontiers of Optoelectronics" on November 17, 2023, reveal a surprising discovery: even trace amounts of chloride in these perovskites drastically reduce the operational lifetime of blue PeLEDs. This negative impact is attributed to the low migration energy barrier of chloride ions in mixed bromide/chloride perovskites. Under electrical bias, chloride ions rapidly vacate the perovskite films, leading to a swift degradation in device performance.

This revelation is significant as it highlights an intrinsic challenge in the use of chloride in blue PeLEDs. The study not only identifies the problem but also underscores the need for novel approaches to stabilize chloride ions within the perovskite structure. Developing such strategies could be key to enhancing the durability and operational lifetime of blue PeLEDs, thereby paving the way for their broader adoption in lighting and display technologies.

The research by Professors Xu and Gao's teams offers a crucial insight into the complexities of perovskite materials and their behavior in LED applications. As the quest for stable, efficient, and vibrant blue LEDs continues, these findings provide a new direction for researchers and industry experts in their ongoing efforts to overcome the challenges faced by blue PeLEDs. The understanding of chloride's role in diminishing the stability of these devices is a critical step forward in the evolution of LED technology, potentially leading to more robust and reliable blue PeLEDs in the future.

Research Report:Role of chloride on the instability of blue emitting mixed-halide perovskites