Polarization-based colour tuning of mixed colloidal quantum-dot thin films using direct patterning.

Colloidal quantum-dots (cQDs) are finding increasingly widespread application in photonics and optoelectronics, providing high brightness and record-wide colour gamuts. However, the external quantum efficiencies in thin-film device architectures are still limited due to losses into waveguide modes and different strategies are being explored to promote the outcoupling of emission. Here we use a template-stripping-based direct-patterning strategy to fabricate linear gratings at the surface of cQD thin films. The linear gratings enhance optical outcoupling through Bragg scattering, yielding bright emission with a strong degree of linear polarization. By patterning linear gratings with different periodicities and orientations onto a film of mixed-colour cQDs, we demonstrate polarization-based active colour tuning of the thin-film emission.