A team of researchers led by Professor Biwu Ma from Florida State University demonstrated a new approach to building efficient and spectrally stable red perovskite LEDs. The team developed a simple solution processing method followed by thermal annealing to prepare highly luminescent ultra-smooth polymer–perovskite composite thin films with tunable emissions from red to deep-red.

Florida U team advanced red perovskite LEDs image

Light emitting diodes (LEDs) incorporating inorganic, organic, or nanoscale materials are highly promising for solid-state lighting and displays. Despite the significant progress achieved in green emitting perovskite LEDs in recent years, blue or red emitting LEDs still remain a challenge with regards to their performance and spectral stability during operation.

The color tuning ability was achieved by utilizing the quantum size effect in quasi-2D cesium lead iodide perovskites with different thicknesses of layered quantum well structures. The new approach overcomes an issue related to the change of emission color due to ion migration and phase separation during the device operation, a common problem present in other red emitting perovskites containing mixed halides.

Optimizing the device architecture, the researchers achieved the most efficient and spectrally stable red perovskite LEDs reported to date, with brightness and EQEs of up to 1392 cd/m2 and 6.23 %, respectively.

The authors stated: “This work demonstrates a new pathway toward high performance perovskite LEDs with desired emission colors, and further establishes metal halide perovskites as new generation solution processable semiconductors for optoelectronic devices”.