Does the sun effect an iphones screen? I've been sunbathing today and my screen won't work now?

My phone has been sat in the sun today, not all day but it was sat on a table in my garden for a while with no shade to cover it, will this effect my screen because it won't work now? If i hold the button long enough siri comes on but the screen is just black

It's probably just overheated, just let it cool down!

I just have a problem seeing it out in the bright sun, other than that it works fine.