Ultra-soft near-infrared perovskite LEDs with over 20% efficiency

Soft near-infrared perovskite light-emitting diodes (PeLEDs) with exceptional external quantum efficiencies (EQEs) play a vital role in soft sensors and biomedical devices, serving as conformal and wearable human–machine interactive interfaces. However, the performance of soft near-infrared PeLEDs still lags behind that of PeLEDs made on rigid substrates, primarily due to the lack of suitable soft electrodes. Here, we report an effective approach to produce high-quality ultra-soft electrodes that are suitable for high-efficiency near-infrared PeLEDs. These electrodes, with outstanding mechanical and optoelectronic properties (greater than the optical transmission of commercially available ITO electrodes), are achieved by sputtering Ti, Ga, and Zr-doped indium oxide (ITGZO) onto a man-made ultra-soft parylene substrate. Combined with an ethanolamine (EA)-engineered nanocrystals (NCs) electron injection layer, the ultra-soft near-infrared PeLEDs exhibit an EQE of 20.2 %. The entire device can be peeled off from the substrate, showing a thickness close to 4 μm. Moreover, the peeled-off ultra-soft PeLEDs demonstrate superior mechanical durability when tested at a 1.0 mm radius of curvature. The weight-to-area ratio of the entire PeLED system, which includes ultralight and ultra-soft electrodes, is 600 times lower than that of conventional devices, indicating their potential for soft conformal biomedical devices on skin.