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Quantum sensors have notably advanced high-sensitivity magnetic field detection. Here, we report quantum sensors constructed from polarized spin-triplet electrons in photoexcited organic chromophores, specifically focusing on pentacene-doped para-terphenyl (0. 1%). We demonstrate essential quantum sensing properties at room temperature: electronic optical polarization and state-dependent fluorescence contrast, by leveraging differential pumping and relaxation rates between triplet and ground states. We measure high optically detected magnetic resonance (ODMR) contrast 16. 8\% of the triplet states at room temperature, along with long coherence times under spin echo and CPMG sequences, T₂=2. 7s and T₂^DD=18. 4s respectively, limited only by the triplet lifetimes. The material offers several advantages for quantum sensing, including the ability to grow large (cm-scale) crystals at low cost, the absence of paramagnetic impurities, and the diamagnetism of electronic states used for sensing when not optically illuminated. Utilizing pentacene as a representative of a broader class of spin triplet-polarizable organic molecules, this study highlights new potential for quantum sensing in chemical systems.
Singh et al. (Wed,) studied this question.