Yep, it's called a "radioisotope thermoelectric generator". Mostly used on satellites.

Betavoltaic devices are exactly what you’re describing. They convert beta radiation (energetic electrons) into electricity in the same way that photovoltaic cells (solar panels) convert photons into electricity. You can create a nuclear battery by putting some radioactive material that decays via beta emission in one of these.

The downside of these devices is that they generate very little power. It takes a dangerous amount of radioactive material to generate the power needed for say a phone or laptop. Commercial betavoltaic devices generate ~tens of microwatts. They’re useful if you need a low power battery somewhere that you don’t want to replace, like in a remote sensor.

Lot of comments about RTGs, but I don't think that's what OP is asking. RTGs convert heat to electricity, same as a conventional power plants

they just do it in a solid state way instead of steam. In RTGs it doesn't matter where the heat comes from; they are not really analogous to solar cells, as the title asks.

In fact, there are consumer products that use the same technology

you can buy a little electric fan that sits on top of a wood stove and, once up to temp, will start spinning. The electricity is generated by the thermal gradient using heat from the stove, essentially the same as an RTG.

This article has a good breakdown. The biggest issue is efficiency. RTGs are around 5-9% efficient. Standard steam cycle generators are around 30% (see this article ) . You get much more usable energy from fuel used in a commercial reactor vice a RTG.

What the hell is this thumbnail?

It works, but if I remember well my material science course, the yield is pretty bad compared to a simple steam-turbine. Therefore engineer chose the simplest and most efficient design. And this is how the most advanced energy source humanity have end-up being controlled by a good old steam machine

No one has directly answered your question.

The answer is yes, you can create photovoltaic cells better optimise to pick up high energy light such as that from nuclear decay (gamma radiation). However, the power generated by photovoltaics is limited more by intensity of the light, and not the energy per photon (wavelength). For physical reasons is hard to capture the energy of high energy light, so gamma photovoltaics are low power concepts.

There is an idea going around to grow diamond with c14 and also harvest that c14 decay with a diamond based photovoltaic. Making everlasting batteries, albeit radioactive and microwatt. (Specifics are probably wrong, working from memory.)

Yup, RTGs exist, but they're impractical for most terrestrial use cases. The problem is that any isotope that's energetic enough to generate meaningful amounts of energy is also going to be somewhere between quite dangerous and insanely dangerous if the container is breached. And unless there are very strong protocols in place for handling the RTG, on a long enough timeline, there's basically guaranteed to be a nuclear accident.

Yes, with RTGs. They are used on mars rovers, for example.

Looking into it, it should be theoretically possible to get a material that decay into beta particles trapped in sphere that would gather these particles and thus electrically charge the sphere.

I don't see how you turn it on or off though, which might be a problem.

There is the nano/nuclear diamond battery thing too, which is supposed to work like this but apparently produces very little energy if any

Yes and we already have and use them. Albeit only on NASA probes leaving earth.

Both of the curiosity rovers use this as their power plant. A bunch of plutonium sits in that little tail like stub on them and generates perpetual power for them.

On of the fusion reactor designs works this way. Sorta.

The reactor creates a magnetic field, then fusion happens, creating a magnetic (or electric… iono. Not a nuclear engineer) field flux in the same coils that created the initial field. Fusion stops, then the flux is ‘harvested’ somehow to generate electricity directly. Then the field is primed again, and fusion happens again. It’s pulsed and happens 60-100 times a second.

I think the company working on this is called Helion.