I don't think there's anything solar that's small enough to fit on the handlebars that would provide anywhere near enough juice to charge a modern phone.

If you're just out riding for the day, the best solution is an external battery with a usb port. They sell a bazillion of them on amazon that provide enough power to ride all day.

For touring where you don't have electric, a hub dynamo is the most likely to work well and consistently. They also sell larger solar panels that you can put on the back of your bike that I've heard of working.