Ruddlesden–Popper Hybrid Lead Iodide Perovskite 2D Homologous Semiconductors - Stoumpos, Constantinos C; Cao, Duyen H; Clark, Daniel J; Young, Joshua; Rondinelli, James M; Jang, Joon I; Hupp, Joseph T; Kanatzidis, Mercouri G (Chemistry of materials, 2016)