Spectral Narrowing and Enhancement of Directional Emission of Perovskite Light Emitting Diode by Microcavity

Perovskite light-emitting diodes (PeLEDs) have attracted much attentions due to the superior optoelectronic properties such as pure spectrum, high photoluminescence quantum yield, tunable emission, and ease of fabrication. Though lots of progresses have been made on PeLEDs and optically pumped lasers, microcavity perovskite lasing device under electrical pumping remains extremely challenging. Microcavity perovskite LEDs can be considered as a step toward laser diode due to the common structure of resonant cavity. In this study, a new type of metal-dielectric microcavity PeLED is designed and fabricated by using 2.5 pairs of TiO2/SiO2 distributed bragg reflector (DBR) and Al as cavity coplanar mirrors. A microcavity device with forward spectral full-width at half-maximum of 11.8 and 9.5 nm, under electrical and optical excitations, respectively, the directional forward emission within 30 degrees is enhanced by 3 times compared to the control device without cavity is realized. To the best of the knowledge, this study demonstrates the narrowest spectrum for three-demisional PeLEDs so far, it helps to expand the color space in display applications and may also serve as a reference device for solution processed perovskite exciton-polariton electroluminescent devices and electrically driven vertical cavity surface emitting lasers due to the similar device structure and processing.