The materials are generally unstable in the moisture of the atmosphere, deteriorating over hours or days.
But researchers in Australia have maintained ~80% of emission despite 10,000 hours of water immersion.
Although this was a photo-luminescence proof-of-concept – emitting light when illuminated by a laser in this case – the technology could be the first step on a road to stable electrically-stimulated light emission or stable photovoltaics.
‘Black’ phase caesium lead iodide was the chosen material, stabilised by forming a composite with a glassy phase of a metal-organic framework through liquid-phase sintering.
The glass acts as a matrix for the perovskite, stabilising perovskite phases through interfacial interactions, which also passivate perovskite surface defects and cause bright narrow-band photoluminescence, according to ‘Liquid-phase sintering of lead halide perovskites and metal-organic framework glasses’, a paper on the subject.
It also improves stability in the face of organic solvents, and exposure to heat, light, air and ambient humidity.
Equally importantly, it locks away the toxic Pb, according to the University.
This is nano-crystal technology, where emission colour can be changed by varying particle size
“Not only can we make these nanocrystals more robust but we can tune their opto-electronic properties with fantastic light emission efficiency and highly desirable white light LEDs,” according to Professor Vicky Chen. “This discovery opens up a new generation of nanocrystal-glass composites for energy conversion and catalysis.”
The University of Queensland St Lucia, worked with the Slovenian National Institute of Chemistry, Shanghai Jiao Tong University, University of Leeds, France’s Laboratoire de Physique des Solides, Nagasaki University, University of Cambridge, European Synchrotron Radiation Facility in France, the Australian Synchrotron, the Civil Aviation University of China, the University of Queensland Brisbane, the China Academy of Engineering Physics, and University of California Santa Barbara.
‘Liquid-phase sintering of lead halide perovskites and metal-organic framework glasses‘ is published in Science.