You'd probably need to pack a multi-mode propulsion system. Launch it so it can get a gravity assist from the Sun, deploy a solar sail after closest approach (or when safe) and ride the light pressure from the Sun to get as much delta-v as you can, then ditch the sail and fire up nuclear-powered electric thrusters for the rest of the trip. Dropping the solar sail part may be a good idea if its weight could be better used as propellant for the ion drive.

Then you have a hope of making the trip in a couple decades