In situ observation of organic single micro-crystal fabrication by solvent vapor annealing

Single crystalline arrays on the micro-scale are of crucial importance for high performance and high integration level of organic electronics. Here we report an in situ observation of organic single crystal formation via solvent vapor annealing on both bare and Au patterned SiO2 surfaces. The results show that micro-sized organic islands absorb solvent to form droplets, and then the molecules inside the droplet nucleates to form single crystals. The technique gives positional control of the single crystal array fabrication which is confirmed by X-ray diffraction and selective area electron diffraction. In combination with the area selective growth on Au electrodes, organic single crystal device arrays such as a photon-detector can be directly fabricated with improved light absorption and detectability.