Journal Article macromolecular crystallography beamline endstation diffractometer photoluminescence 2D layered perovskites 3D-printed holders IMISX Macromolecular Substances Research Support, Non-U.S. Gov't collection strategy cryogenic sample handling crystals synthesis diffraction data fixed targets high-throughput in meso in situ serial X-ray crystallography low-dimensional perovskites microcrystallography microspectrophotometer multi-axis goniometry multiple quantum well optical efficiency organic cations out-of-plane excitons post-crystallization treatments sample changers white emission