While quasi-2D perovskites made with organic spacers co-crystallized with inorganic cesium lead bromide can enable near unity photoluminescence quantum yield at room temperature, LEDs made with such quasi-2D perovskites tend to degrade rapidly - which remains a major bottleneck in this field.
Now, researchers from SUNY University at Buffalo, Texas A&M University, Brookhaven National Laboratory, Missouri University of Science and Technology, National Taiwan University and Yonsei University have shown that the bright emission originates from finely tuned multi-component 2D nano-crystalline phases that are thermodynamically unstable.
The bright emission is extremely sensitive to external stimuli and the emission quickly dims away upon heating.
After the team performed detailed analysis of their optical and morphological properties, the degradation was attributed to 2D phase redistribution associated with the dissociation of the organic spacers departing from the inorganic lattice.
To circumvent the instability problem, a diamine spacer was suggested, that has both sides attached to the inorganic lattice. The diamine spacer incorporated perovskite film showed significantly improved thermal tolerance over maintaining a high photoluminescence quantum yield of over 50%, which will make for a more robust material for lighting applications. This study guides designing quasi-2D perovskites to stabilize the emission properties.
