Tunable and flexible deep-ultraviolet bandpass filters based on micro- and nanoparticle/polydimethylsiloxane hybrid membranes

Abstract Deep-ultraviolet (DUV) bandpass filters play an important role in the fields of modern environmental disinfection and sterilization. A novel low-cost optical scattering material that can be used to manufacture flexible DUV bandpass filters is proposed. Considering both the refractive index matching condition and Rayleigh-Gans-Debye (RGD) scattering theory, the calcium fluoride (CaF2)-doped polydimethylsiloxane (PDMS) DUV bandpass filter shows over 90% transmittance near the peak wavelength of 272.5 nm. Strain measurements result in relatively stable peak wavelengths with stretching ratios of 12%. A temperature response of 1.5 nm °C−1 is measured experimentally. To simulate the DUV light filtering characteristics of the device, an improved random walk scattering model is developed based on a Monte Carlo numerical simulation. To verify the tunability of the transmittance spectra of the devices, a 10 nm blueshift of the peak wavelength is obtained by doping 50 vol% low-molecular-weight PDMS in the original PDMS matrix, and a 17 nm redshift is observed upon doping 1.4 wt% CdSe/ZnS colloidal quantum dots (CQDs). The realization of tunable and flexible DUV bandpass filters paves the way towards the development of environmental purification equipment and wearable photonic devices.