Stretchable Hexagonal Diffraction Gratings as Optical Diffusers for In Situ Tunable Broadband Photon Management

A stretchable transmissive hexagonal diffraction grating, which has the potential to act as an optical diffuser, is demonstrated. Leveraging the simplicity of the self-assembly fabrication process, the photon manipulation capability of polystyrene nanosphere arrays, and elastomeric properties of polydimethylsiloxane, the proposed device is capable of reproducible in situ tuning of both diffraction efficiency and spectral range. While being able to achieve maximum diffraction efficiencies of about 80%, the device displays highly efficient and broadband light diffusion fairly independent of incident light polarization and angle of incidence. Due to its efficient and tunable diffraction capabilities, one potential application of the reported device can be broadband photon management in solar cells and photodetectors by significant increase of the light path length inside the light-absorbing thin films of these devices. As a proof of concept, the proposed optical diffuser is utilized for light absorption enhancement in colloidal quantum dot semiconductor thin films. The demonstrated devices enable integration of cheap and widely used materials with simple cost-effective fabrication for photon management in optics, photonics, and optoelectronics.