- The full article entitled “A New Approach Exploiting Thermally Activated Delayed Fluorescence Molecules to Optimize Solar Thermal Energy Storage” can be found at the Nature Communications website at https://www.nature.com/articles/s41467-022-28489-0
- Authors: Fan-Yi Meng, I-Han Chen, Jiun-Yi Shen, Kai-Hsin Chang, Tai-Che Chou, Yi-An Chen, Yi-Ting Chen, Chi-Lin Chen, Pi-Tai Chou*
We propose a new concept exploiting thermally activated delayed fluorescence (TADF) molecules as a photosensitizer, storage unit and signal transducer to harness solar thermal energy storage via coupling with norbornadiene (NBD) → quadricyclane (QC) reaction (see Figure 1b). The proof of concept is made by synthesizing molecule composites based on a TADF core phenoxazine–triphenyltriazine (PXZ-TRZ) anchored with norbornadiene, yielding compounds PZDN and PZTN with two and four NBD units, respectively (Figure 1b). Upon visible-light excitation, energy transfer takes place to the triplet state of NBD, followed by the NBD → quadricyclane (QC) conversion that can be monitored by changes of steady-state or time-resolved fluorescence (Figure 1c and 1d). The small S1-T1 energy gap offers advantage in optimizing solar excitation wavelength. Upon tuning the molecule’s triplet state-energy lower than that of NBD’s (61 kcal/mol), demonstrated by another composite PZQN, the efficiency of NBD → QC conversion decreases drastically. Upon catalysis, the reverse QC → NBD reaction takes place at room temperature, bring the stored chemical energy back to heat with excellent reversibility.
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Figure 1. (a) Previous reports on the NBD photosensitization work (b) current energy storage systems for of the MOST process in the NBD-QC system. (c) The fluorescence intensity as a function of the photolysis time. (d) The lifetime of delayed fluorescence as a function of the photolysis period.