Semiconducting π-extended porphyrin dimer and its characteristics in OFET and OPVC

• New class of π-extended porphyrin dimer has been successfully synthesized.
• The OFET devices based on porphyrin dimer show excellent mobility.
• Due to the solubility, the device fabricated from toluene and THF mixed solvents shows higher mobility.
• Annealing is an essential process to increase the crystallinity of π-extended porphyrin dimer based thin-film.

Porphyrin is considered as one of the best candidates for various organic electronic devices, due to its molecular planarity and π-conjugation. Particularly, for the good performing OFETs based on porphyrin derivatives, they should have high crystallinity and close π–π stacking distance in solid state. However, π-extended dimeric porphyrin has never been introduced as a charge transport layer in OFETs. In this regard, we report here on the design and synthesis of new solution processable semiconducting π-extended porphyrin dimer (PD-1), and its OFET and OPVC characteristics. Due to strong π–π interactions, PD-1 showed high crystallinity in film state which displayed an excellent electrical characteristics with high hole mobility of 0.026 cm2/Vs and high current on–off ratio of >105, when the device was fabricated in the mixed solvents of toluene and THF. This mobility is 1000 times better than that of a device fabricated from a solution either THF or toluene exclusively. Furthermore, the photovoltaic performance of PD-1 device shows a PCE of 0.58%. The effective π-conjugation and molecular planarity of π-extended dimeric porphyrin (PD-1) can lead to significant changes in the electrical characteristics of the devices.

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