Modal gain tailoring by flat stamping of thin colloidal films

Post-synthetic tailoring and improvement of the light-emitting material properties is an important direction for optimization of solution processible LEDs and recently emerged laser diodes based on nanocrystals. In this study, we demonstrate modal gain engineering by flat stamping light-emitting films of core/alloyed shell CdSe/CdZnS nanoplatelets. This film modification approach affects the volume density occupation (D) of the emitters in the film and allows for control of the layer thickness while keeping surface roughness low and uniformity high. The achieved level of control of the mode confinement factor (Г) and optical gain is promising for better integration with resonators and multilayered structures. Careful accounting of such parameters makes it possible to achieve higher D values and increase the modal gain up to ∼2.39 times in comparison with standard spin-coating films. The modal gain enhancement and the Г factor control allow us to maximize the optical gain in light-emitting devices and facilitate low-threshold lasing.