Triazine and Porphyrin-Based Cross-Linked Conjugated Polymers:Protonation-Assisted Dissolution and Thermoelectric Properties

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(−6650μV K^(−1))and electronic conductivities(0.042 S cm^(−1)),yielding a power factor of 185μW 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.