Science Daily  September 6, 2022
Researchers in Germany have developed an organic thin-film sensor that describes a completely new way of identifying the wavelength of light and achieves a spectral resolution below one nanometer. The principle of operation of the new sensor is that light of unknown wavelength excites luminescent materials in a hair-thin film. The film consists of a mixture of phosphorescent and fluorescent entities, which absorb the light under investigation in different ways. The intensity of the afterglow can be used to infer the wavelength of the unknown input light. They exploited the fundamental physics of excited states in luminescent materials that light of different wavelengths excites in such a system certain proportions of long-lived triplet and short-lived singlet spin states. By reversing that dependence, they could identify light wavelengths. Using this strategy, they achieved sub-nanometer spectral resolution and successfully tracked minor wavelength changes of light sources. According to the researchers the novel sensors can also be used in counterfeit protection…read more. Open Access TECHNICAL ARTICLEÂ
Experimental setup for single-film wavelength sensing. Credit: Advanced Materials, 04 August 2022Â