Fig. 3
From: Cellular interfaces with hydrogen-bonded organic semiconductor hierarchical nanocrystals
Control of internal crystal structure. Polymorphism can be controlled by modulating reaction time and coordinating chemical additives. a SEM micrographs of α 2, β and γ crystals. b X-ray diffraction, confirming the phase-pure quality of the colloidal samples, c absorbance and d luminescence of each sample. The upper row of SEM images shows the hierarchical nano-dagger modification, while the lower row shows hierarchical nanoneedle assemblies
