Hybrid Systems Based on Porous Silicon Photonic Crystals, Liquid Crystals, and Quantum Dots

Porous silicon (pSi) photonic crystals are of much interest for both basic and applied research. Embedding luminophores into these structures allows controlling their emissive properties, which holds promise for laser and display applications, as well as for investigation of light-matter interaction. In addition, the development of photonic crystals in which the spectral position of the photonic band gap can be shifted by external factors offers prospects for designing new photonic and optoelectronic materials. Here, a technology for the fabrication of hybrid systems based on quantum dots (QDs) and nematic photochromic liquid crystal mixtures placed inside pSi microcavities (MCs) is suggested. When QDs are placed inside a pSi MC, their photoluminescence (PL) spectrum narrows due to the Purcell effect and weak coupling between the exciton transitions in the QDs and the eigenmode of the pSi MC. Exposure to UV light causes a shift of the PL spectrum of the hybrid structure to longer wavelengths, whereas exposure to visible light shifts the spectrum back to shorter wavelengths. This photo-optical response can be used to control the PL properties of the hybrid systems and design new photonic, optoelectronic, and sensing devices on their basis.