No, way too little sun out here. The sun is just a dot far away. The Voyagers both use RTGs, radioisotope thermoelectric generators. Decaying plutonium, essentially. That's for the electrically powered systems. The thrusters use liquid hydrazine, which is common for those kind of thrusters.

Edit: There's more about that in the NASA link in a sibling comment.

Solar has nothing to do with it. Voyager uses hydrazine, of which over 80% has been used up over the years. They simply use not that much of it as it's not for thrust, but for aiming at Earth more or less.

Even with something like an ion engine (which I'm not sure were available when Voyager was launched), you would need leftover reaction mass.

> How would that work exactly?

Light sails. Laser propulsion. Photon rockets. None of which apply to Voyager. But none of which are laughably dismissible.