I am having a temporary black screen after closing all apps and returning to the home screen with my iPhone 6 Plus running iOS 9.1 But I think I might have found a fix and it's related to the dynamic wallpaper. I changed my wallpaper to a still for my home screen instead of using one of Apples Dynamic pictures. So far the black screen does not appear when you close the apps and go back to the home screen. My iPhone was updated OTA and my iPad Air was updated via iTunes both have this issue, so it might be a iOS issue they need to fix. I spoke to Apple support and they logged this issue for their engineers, hopefully it will be fixed in the next update. Also had my hardware tested at a Apple service center and showed no issues. Is anybody else having this issue ?