The team created micro- and nano-perovskite LEDs (micro- and nano-PeLEDs)
with pixel sizes ranging from hundreds of microns to 90 nanometers , the smallest LED pixels disclosed to date. At the same time, they created an LED pixel array with an
ultra-high resolution of 127,000 PPI , setting a record for the highest resolution of all types of LED arrays
The paper states that the current manufacturing cost of III-V semiconductor Micro-LEDs is high, and when they are reduced to about 10 microns or smaller, the efficiency will drop sharply, so perovskite LEDs (PeLEDs) show high performance at low processing costs. Since the room temperature electroluminescence (EL) demonstration of halide perovskites in 2014, substantial progress has been made in device performance.
High EQEs are 20-30%, and the working life is close to that of organic LEDs.The team proposed a local contact process. A patterned window made by photolithography was introduced in the additional insulating layer to ensure that the pixel area is away from the electrode edge. This method will avoid the perovskite material being easily exposed at the electrode edge, resulting in non-radiative energy loss, thereby reducing the efficiency of the LED.
Based on this strategy, the team created green and near-infrared perovskite LEDs, and the size reduction effect only began to appear at an extremely small size of about 180 nanometers, when the efficiency of nano-PeLED dropped to 50% of the maximum value. This shows that in the ultra-small size range, micro and nano-PeLEDs are more efficient than Micro-LEDs based on III-V semiconductors, the latter of which has a significant drop in efficiency when the size is below 10 microns.It is worth noting that the team has obtained the smallest LED device so far, with a pixel density of up to 127,000 PPI, which has set a new record for all LED arrays. In addition, the team
has successfully developed a prototype active matrix micro-PeLED display based on a commercial thin-film transistor (TFT) array, verifying its potential for application in the field of high-resolution displays.