Researchers from China's Zhejiang University, in collaboration with the University of Cambridge, have created the world’s smallest light-emitting diodes (LEDs), measuring just 90 nanometers in size - around the size of a virus. According to a study published in the science journal Nature, these nano-perovskite LEDs (nano-PeLEDs) achieve a record pixel density of 127,000 pixels per inch (PPI), surpassing existing LED technologies.