Analysis crew reveals why water moisture impacts quantum crystals

The crew, led by Professor Jiwoong Yang from the Division of Vitality Engineering at DGIST, and in collaboration with the crew led by Professor Jungwon Park from the Faculty of Chemical and Organic Engineering at Seoul Nationwide College, decided the moisture- (water-) induced degradation mechanism of semiconductor nanocrystal quantum dots.

The joint analysis crew developed the next-generation imaging platform for in-situ liquid-phase transmission electron microscopy (TEM), which can be utilized to disclose the response intermediates and atomic unit response paths that exist within the degradation course of, thereby taking one step nearer to the commercialization of nanocrystal quantum dots.

Semiconductor nanocrystal quantum dots discover intensive functions in numerous fields akin to bioimaging, optoelectronic gadgets, and catalysts because of their advantageous options, together with dimension and shape-dependent band gaps, excessive lamp effectivity, and slim full width at half most. Nevertheless, in addition they exhibit drawbacks akin to diminished stability when uncovered to moisture and oxygen in comparison with bulk semiconductor crystals.

Consequently, quite a few research are underway to create semiconductor nanocrystal quantum dots with enhanced stability towards the influence of moisture and oxygen. However, the event course of faces challenges as a result of the particular “degradation” mechanism, which causes deterioration of their properties because of exterior elements, has not been totally defined.

Research have been performed utilizing spectrometry, X-ray scattering, and diffraction evaluation to establish the degradation mechanism; nonetheless, these strategies might solely establish the modifications in optical and bodily properties of nanocrystals within the moisture-induced degradation course of, offering solely common data on structural modifications.

Furthermore, there are limitations in revealing the existence of assorted atomic unit response patterns and response intermediates which will happen in particular person nanoparticles, as it’s tough to find out the structural change mechanism of particular person nanocrystals.

Accordingly, Professor Jiwoong Yang’s crew at DGIST devised a way utilizing in-situ liquid-phase TEM, enabling the remark of the response technique of particular person nanoparticles in real-time. Particularly, liquid cells able to each response management and real-time ultra-high-resolution imaging have been wanted to establish the moisture-induced degradation mechanism.

For this goal, the crew developed “graphene-based next-generation liquid cells” that possess each features. These next-generation liquid cells are designed to regulate the combination of two totally different liquids by means of extraordinarily skinny graphene membranes.

Moreover, analysis was performed to disclose the degradation mechanism utilizing “cadmium sulfide (CdS),” which is a well known crystallization methodology for nanocrystal quantum dots. The outcomes revealed that “cadmium sulfide (CdS)” semiconductor nanocrystals bear decomposition by forming amorphous intermediates comprised of Cd(OH)x in the course of the degradation course of.

Furthermore, the presence of this amorphous intermediate results in an irregularly formed crystal floor construction in the midst of the response, which is totally different from the beforehand studied degradation mechanism of steel nanocrystals. This confirmed the significance of defending the floor of semiconductor nanocrystals, because the moisture-induced structural degradation of semiconductor nanocrystals is irreversible and initiates from the floor.

“Moisture-induced degradation has been a key issue inflicting difficulties in commercializing semiconductor nanocrystal quantum dots,” said DGIST Professor Jiwoong Yang. “The degradation mechanism revealed on this research is predicted to considerably contribute to the longer term improvement of quantum supplies.”

The paper is printed within the journal ACS Nano.