Unlocking efficient light-energy conversion with stable coordination nanosheets | Hacker News Reader

Unlocking efficient light-energy conversion with stable coordination nanosheets

tus.ac.jp

48 pointsrustoo13 comments

> "With these results, the scientists are thrilled about the prospects of CONASH in commercialized optoelectronic applications."

Headline implies PV, article talks about detection.

See figure 3: https://onlinelibrary.wiley.com/doi/10.1002/advs.202100564

Doesn't the measurement of current in the presence of light mean photo-voltaic?

Yes, but photo-voltaic also implies energy conversion for power operations, like to run appliances. This is energy conversion for detection, like a sensor.

I assume this photodetector also uses the photoelectric effect like PV cells. Does anyone know why they wouldn't just use the more established pv tech? Said only getting efficiency of 6%.

Is there something fundamentally different about a photodetector vs. a pv cell that necessitates using different photon hitting material?

I'm just guessing here, but having "a short response time to changes in input" might not be a priority for PV technology

The reason they aren't using more established pv tech is that they're demonstrating a new class of photoelectric material. This material may be cheaper to produce than more established pv materials and may be easier to tune to specific wavelengths, which is of interest to photodetection

Can someone smarter than I explain what this means? More efficient solar panels?

It's demonstrating that a new class of materials which may be suitable for solar cells which previously had a degradation problem can be made more degradation resistant.

The interest in this class of materials is that they can be made cheaply. Making silicon for solar cells is an energy intensive process requiring high temperatures. The process for making this material doesn't require very high temperatures or use much energy. Once you have the components, making the material is very similar to growing say salt crystals.

Organic molecules with negatively charged components combine with metal ions forming a sheet structure mostly dictated by the shape of the organic molecule and type of metal ion used. This brings us to the other reason why this class of materials is interesting, they're somewhat programmable. By using different organic molecules with different shapes or different metal ions we can get different properties.

In addition, unlike nanomaterials like graphene we can make similar materials(metal organic frameworks) by the ton.

Now, the material they made isn't very good as a solar cell or a photodetector. The efficiency at converting a single wavelength of 365 nm(UV) light to electricity isn't very high. In addition, the response time is something like 40 ms, which seems pretty high for a photodetector. But the main point is that it doesn't degrade much under harsh UV radiation(CORRECTION: they measure degradation under exposure to air), with photocurrent 94% of the initial value after more than 60 days of aging.

I'd say it's worth watching the development of this type of material. Part of the reason perovskite solar cells generate so much hype is that their rate of efficiency improvement with time is high. The same may happen with this class of materials, but at the current time there's no indication of rapid improvement.

Thank you for the detailed insight.

Can I ask you about this?:

>But the main point is that it doesn't degrade much under harsh UV radiation, with photocurrent 94% of the initial value after more than 60 days of aging.

Does not that mean that there is 3% degradation per month or 36% per year (i.e. the whole stuff lasts roughly 3 years only at this stage)?

Or once it gets to 94% after 2 months it somehow "settles"?

They don't have that information, but I suspect degradation may be continuous. There is a nice plot in the supplementary information on page 5 of how this material compares to other materials[0].

Also, I need to make a correction. I said stability was exposure under UV light, when in fact stability under exposure to air was measured. Encapsulation could probably make the material last longer.

[0]https://onlinelibrary.wiley.com/action/downloadSupplement?do...

I see, hopefully once encapsulated they will last much more, otherwise, if it is linear, you would need replace them every year or so during which you go from 100% to 74%.

Based on following tons of science news for decades: this means nothing. A new hyper-efficient solar panel is discovered almost as often as a battery that lasts weeks/charges in minutes.

Electrochemists may one day invent a combined battery and solar panel.

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