Advancements in the Improvement of Optical Outcoupling Efficiency for Perovskite LEDs

In the past 10 years, the development of perovskite light-emitting diodes (PeLEDs) was fast. Due to the excellent properties of high brightness and color purity, multiple color emission, and cost-effective fabrication technology, PeLEDs have been very promising in semiconductor lighting and display applications. In an effort to achieve high-efficient PeLED devices, researchers have devoted themselves to explore and optimize the emitted materials and device structures. Among various research approaches, raising the optical outcoupling efficiency ( η out ) of PeLED through light management strategies is very important for further promoting device performances, which is due to that approximately 80% of the photons generated internally are captured or worn out in different optical modes in the device. In this review, the latest researches on optical outcoupling regulations in PeLED are outlined, which mainly focus on photophysical properties and implementation methods. As the key part of this review, implementation strategies are classified into the optimization of characteristics of functional materials (refractive index, film thickness, anisotropy, and photon recovery) and adjustment of device architecture (patterned nanostructures, photonic crystals, metal nanostructures, and external couplers). Additionally, a prospect of the future directions and development trend for this research field is presented in order to achieve ultra-efficient PeLED and future commercial applications.