High‐Radiance Near‐Infrared Perovskite Light‐Emitting Diodes with Improved Roll‐Off Degradation.

The external quantum efficiency (EQE) of state‐of‐the‐art near‐infrared perovskite light‐emitting diodes (PeLEDs) is now approaching the limit set by the out‐coupling efficiency. However, there is plenty of room for enhancing these devices' radiance and the EQE roll‐off. This work reports how conductive and passivating additives construct efficient high‐radiance near‐infrared PeLEDs with improved EQE roll‐off. Specifically, the synergistic effect of 1,4‐phenylenediacetic acid (PDA) and 5‐aminovaleric acid (5‐AVA) is used to regulate the quality of the perovskite emissive layer, thereby enhancing the roll‐off threshold of injection currents (a value at which the device EQE or radiance starts degrading). According to in situ structural evolution analyses from the perovskite precursor to the perovskite crystal, the presence of PDA within the perovskite precursor solution can produce an intermediate phase with 5‐AVA and formanmidinium cation, which can retard the perovskite nucleation and crystal growth, leading to improved perovskite film quality. The resulting champion PeLED delivers among the highest radiance of 505 W sr−1 m−2 and a peak EQE of 17.56%. More importantly, the improved PeLED shows a well‐retained radiance of 80% at a current injection density of up to ≈1800 mA cm−1, opening a new avenue for high‐radiance PeLEDs with improved roll‐off degradation. [ABSTRACT FROM AUTHOR]