Citation: Mao, Lingling; Tsai, Hsinhan; Nie, Wanyi; Ma, Lin; Im, Jino; Stoumpos, Constantinos C.; Malliakas, Christos D.; Hao, Feng; Wasielewski, Michael R.; Mohite, Aditya D.; Kanatzidis, Mercouri G. (2016). Role of Organic Counterion in Lead- and Tin-Based Two-Dimensional Semiconducting Iodide Perovskites and Application in Planar Solar Cells. Chemistry of Materials, 28, pp. 7781-.