White‐Emissive Self‐Assembled Organic Microcrystals

Organic semiconductor micro‐/nanocrystals with regular shapes have been demonstrated for many applications, such as organic field‐effect transistors, organic waveguide devices, organic solid‐state lasers, and therefore are inherently ideal building blocks for the key circuits in the next generation of miniaturized optoelectronics. In the study, blue‐emissive organic molecules of 1,4‐bis(2‐methylstyryl)benzene (o‐MSB) can assemble into rectangular microcrystals at a large scale via the room‐temperature solution‐exchange method. Because of the Förster resonance energy transfer, the energy of the absorbed photons by the host matrix organic molecules of o‐MSB can directly transfer to the dopant organic molecules of tetracene or 1,2:8,9‐dibenzopentacene (DBP), which then emit visible photons in different colors from blue to green, and to yellow. More impressively, by modulating the doping molar ratios of DBP to o‐MSB, bright white‐emissive organic microcrystals with well‐preserved rectangular morphology can be successfully achieved with a low doping ratio of 1.5%. These self‐assembled organic semiconductor microcrystals with multicolor emissions can be the white‐light sources for the integrated optical circuits at micro‐/nanoscale.