Unraveling the relationship between bulk structure and exposed surfaces and its effect on the electronic structure and photoluminescent properties of Ba0.5Sr0.5TiO3: A joint experimental and theoretical approach

•Ba0.5Sr0.5TiO3 (BST) samples were synthesized by the polymeric precursor method.•A deep analysis of crystalline structure, electronic and photoluminescent properties is presented combining experimental and theoretical efforts.•Structural disorder along Ti-O paths play a key role in BST electronic structure.•Exposed surfaces of BST induces a narrowed band gap enabling optical and electronic applications.