For my last desert hike I did lots of research on solar chargers. It was dissapointing at best.
You will always need a solar charger that includes a battery (usually you're hiking during the daytime, when the sun is up and the solar panel exposed on top of your pack - you will not want to have your precious smartphone always plugged into the charger, thus making it difficult to use and prone to cable/plug defect.
So you end up carrying a solar panel, a battery pack and some cables and electronic box.
If all this stuff is made lightweight, its flimsy and will break just like that.
If everything is made professional style it will be heavy and expensive, and still you can eaysily crack the panel or rip a plug.
There are battery packs that include a small solar panel. Forget about these, this is maybe good for eliminating the self-discharging of the battery, but will not harvest any usable solar power.
A guy I was hiking with had one dangling from his pack - useless stuff.
I ended up carrying a battery pack that got the best review in a serious European computer magazin. (Varta 6000).
BTW, I also did some tests with the Biolite woodburning stove, that claims to be able to charge your phone.
It may be sufficient to charge an old cell phone to a level that you can make a quick call, but to stay realistic, it will not be able to charge a smartphone sufficiently, unless you are willing to stay up and nurse the stove for the whole night.