Amide Hydrochloride Molecules Enable Energy-Efficient Near-Infrared Perovskite LEDs

Perovskite light-emitting diodes (PeLEDs) have made significant advancements over the past decade. However, despite their rapid improvements in external quantum efficiencies (EQEs), progress in energy conversion efficiencies (ECEs) remains slow, limiting their applications in areas such as smart wearables and sensing, where low power and low voltage operation of devices is of critical importance. The normally unsatisfactory ECEs of PeLEDs could be attributed to the low EQEs resulting from the dominant trap-assisted nonradiative recombination at low current densities and the high operating voltages required for sufficient photon output. Here, we demonstrate FA_1-xCs_xPbI₃ perovskite LEDs with simultaneously enhanced EQEs and ECEs through the introduction of a β-alaninamide hydrochloride (BAH) molecular passivator. These molecules effectively passivate defects and promote the formation of the more desirable α-phase perovskites, resulting in suppressed nonradiative recombination losses and reduced operating voltages. The resultant near-infrared (795 nm) PeLEDs exhibit peak EQEs of ∼23.6% at 2 mA cm^-2 and peak ECEs of ∼24.6% at 0.79 mA cm^-2. Owing to the broad processing window of our method, excellent device performance over an extensive wavelength range (723-795 nm) is achieved. These findings contribute to the development of energy-saving and scalable perovskite LEDs.