Triazine and porphyrin-based cross-linked conjugated polymers: Protonation-assisted dissolution and thermoelectric properties

Abstract

As two pivotal functional segments, triazine and porphyrin can be coupled to form a highly cross-linked conjugated polymer. Although the obtained conjugated polymers are almost insoluble in most solvents, a small amount of protonic acid can cause the formation of a colloidal solution of polymers. The dissolution process has proved to be a surface charge effect induced by protonation of porphyrin units in the polymer framework. High-quality conjugated polymer films have been prepared on diverse substrates by solution drop-casting and then used for thermoelectric (TE) applications. The films exhibit remarkable TE performance with high Seebeck coefficients (−6650 μV K−1) and electronic conductivities (0.042 S cm−1), yielding a power factor of 185 μW m−1 K−2, which, collectively, are the highest among all reported n-type organic TE materials. This work may pave the way for the design and development of solution-processed, cross-linked polymer films as promising TE materials. (Figure Presented)