High-Efficiency Top-Emitting Green Perovskite Light Emitting Diode with Quasi Lambertian Emission

Metal halide perovskite light-emitting diodes (PeLEDs) are regarded as alternative candidates for next-generation display technologies due to their high efficiency, superior color purity, tunable bandgap. However, the research on transparent and top-emitting PeLED with Lambertian emission profile significantly lags behind due to optical microcavity effect, which has become one of the main obstacles for potential practical display applications. Here, strategies are developed to suppress the microcavity effect by enhancing the transmission of the semitransparent electrode and extending the optical cavity length. Besides, a nanopatterned structure is incorporated to suppress the surface plasma and waveguide mode effect. Based on the above combination strategies, a transparent PeLED yields a record total external quantum efficiency (EQE) of 16.1% with Lambertian emission by depositing high refractive index molybdenum oxide on the semitransparent cathode. Besides, a high EQE of 13.6% of a top-emitting device with quasi-Lambertian emission is achieved by stretching the optical distance between two reflective layers and enhancing the transmission of the semitransparent electrode. The nanopatterned structure enables suppressed waveguide mode and surface plasmon polariton dilapidation of top-emitting PeLEDs. This work paves a path to design transparent and top-emitting PeLEDs for potential applications in both traditional and novel transparent displays.

Automated summary

Strategies have been developed to suppress the microcavity effect in transparent and top-emitting PeLEDs by enhancing electrode transmission and extending the optical cavity length. A record high total external quantum efficiency (EQE) of 16.1% in a transparent PeLED with Lambertian emission was achieved by depositing high refractive index molybdenum oxide on the semitransparent cathode. Additionally, a high EQE of 13.6% was achieved in a top-emitting device with quasi-Lambertian emission by increasing the optical distance between reflective layers and enhancing electrode transmission. The nanopatterned structure effectively suppressed waveguide mode and surface plasmon polariton dilapidation in top-emitting PeLEDs, paving the way for potential applications in both traditional and novel transparent displays.