Electronic structures and chemical reactions at the interface between Li and regioregular poly (3-hexylthiophene)

► The interfacial structures of Li/P3HT have been studied by SRPES and XPS. ► The reactions of Li with both S and C atoms of P3HT are found. ► Li diffuses much deeper than Ca to react with P3HT. ► Energy level alignment diagram of Li/P3HT interface is derived.