Role of Small Organic Molecules in Perovskite Light‐Emitting Diodes: Applications, Mechanisms and Prospects

Abstract Perovskite light‐emitting diodes (PeLEDs) has emerged as one of the most promising technologies for the next generation of lighting and high‐definition display applications due to their exceptional color purity, tunable color emission, and low material costs. In the past eleven years, PeLEDs have made remarkable progress as researchers have come up with many innovative approaches. Among them, additive engineering based on small organic molecules (SOMs) has been demonstrated as one of the most effective strategies to enhance the external quantum efficiency (EQE) and stability of PeLEDs. Notably, the champion EQEs for red, green, and blue devices cannot be realized without the participation of SOMs. Here, this paper first reviews the development of PeLEDs, followed by a focused discussion on the specific application and mechanism of SOMs in PeLEDs. Lastly, it analyzes the challenges and provides an outlook on their future development.