Wavelength-Controlled Organic Microlasers Based on Polymorphism-Dependent Intramolecular Charge-Transfer Process

Wavelength-tunable micro/nanoscale lasers are particularly attractive as indispensible building blocks for various ultracompact photonic devices. Polymorphic organic materials display distinct emission colors in different crystal forms, providing the potential possibility in tailoring the lasing wavelength. Here we report wavelength-controlled microlasers based on the polymorphism-dependent intramolecular charge-transfer (ICT) process in organic microcrystals. With different solution-phase self-assembly methods, three kinds of microstructures were prepared from the same organic ICT compound, where the different crystal structures offer completely distinct molecular environments, having a significant influence on the excited-state ICT process and therefore the emission wavelength. As a result, we realized three different color lasing actions in these three kinds of organic ICT microcystals under two-photon pumping. The results demonstrated here provide useful insights for the rational design of miniaturized lasers with desired performances.