“…Compared with 3D HOIPs, two-dimensional (2D) HOIPs have relaxed steric constraints. Thus, the choice of inorganic ions (e.g., Cu 2+ , Pb 2+ , Eu 2+ , Sn 2+ ) and organic ions (e.g., dye cation and phenyl-methylammonium cation) in 2D HOIPs are much more abundant than that in 3D HOIPs. − For instance, oligothiophenes were used to tailor the band structure of 2D HOIPs at the molecular level. , In addition, the postprocessing of organic cations including polymer crosslink can greatly modify the properties of 2D HOIPs …”