بسم الله الرحمن الرحيم
It is not permissible to touch the screens of the mobile and tablet without wudhu if there is Quranic text displayed on the screen. If there is a back cover or flip cover (phone case) over the body of the device, then it is permissible for the person without wudhu to recite the Quranic text (holding the device) without touching the screen.
أفضل التطبيق العصري على مسائل القدوري
للمفتي محمد أشرف الاشاعتي
Vol.1 Pg.210