Analysis staff reveals why water moisture impacts quantum crystals

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

The joint analysis staff 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 in depth functions in numerous fields reminiscent of bioimaging, optoelectronic units, and catalysts as a consequence of their advantageous options, together with dimension and shape-dependent band gaps, excessive lamp effectivity, and slender full width at half most. Nonetheless, in addition they exhibit drawbacks reminiscent of decreased stability when uncovered to moisture and oxygen in comparison with bulk semiconductor crystals.

In consequence, quite a few research are underway to create semiconductor nanocrystal quantum dots with enhanced stability in opposition to the impression of moisture and oxygen. Nonetheless, the event course of faces challenges as a result of the precise “degradation” mechanism, which causes deterioration of their properties as a consequence of exterior elements, has not been totally defined.

Research have been carried out utilizing spectrometry, X-ray scattering, and diffraction evaluation to establish the degradation mechanism; nevertheless, 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 staff at DGIST devised a technique utilizing in-situ liquid-phase TEM, enabling the remark of the response technique of particular person nanoparticles in real-time. Specifically, 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 staff developed “graphene-based next-generation liquid cells” that possess each capabilities. These next-generation liquid cells are designed to manage the combination of two completely different liquids by extraordinarily skinny graphene membranes.

Moreover, analysis was carried out to disclose the degradation mechanism utilizing “cadmium sulfide (CdS),” which is a widely known crystallization technique for nanocrystal quantum dots. The outcomes revealed that “cadmium sulfide (CdS)” semiconductor nanocrystals bear decomposition by forming amorphous intermediates comprised of Cd(OH)x throughout 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 completely 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,” acknowledged DGIST Professor Jiwoong Yang. “The degradation mechanism revealed on this examine is anticipated to considerably contribute to the longer term improvement of quantum supplies.”

The paper is revealed within the journal ACS Nano.