Although various donor−acceptor (D−A) small molecules with high power conversion efficiency have been reported, D−A small molecules with high field-effect mobility are still rare. In this work, two new A−D−A small molecules with a rigid indacenodithieno[3,2-b]thiophene (IDTT) moiety as the central core and both ends capped with strong electron-withdrawing indole-2,3-dione (IDD) and N-substituted pyrrolo[2,3-b]pyridine-2,3-dione (IDD-N) were synthesized and characterized for applications in solution-processable organic field-effect transistors (OFETs). A N atom was introduced to the IDD units to enhance the planarity and structural ordering by noncovalent interactions, leading to a dramatic effect on the small molecule. The unsubstituted small molecule (IDTT−IDD) did not show any field-effect performance, whereas an encouraging hole mobility of 7.7 cm 2 V −1 s −1 with an average mobility of 6.1 cm 2 V −1 s −1 was obtained for solution-processable OFETs based on the Nsubstituted one (IDTT−IDD-N). This work provided a simple and effective molecular strategy for the design of D−A small molecules for high-performance solution-processable OFETs.

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A single-layer, quartz-supported frequency selective surface (FSS) with a gear-shaped metallic array is proposed for 6G communication. Full-wave simulation, along with the method of equivalent circuit, is applied to investigate the transmission characteristics, while the distributions of surface current distribution, as well as electric field and magnetic fields, are studied to further interpret the transmission mechanism. The simulation indicates that the resonant frequency of 131 GHz with an attenuation of −40 dB can be obtained and the relative bandwidth approximates to 12%. The transmission response of the fabricated FSS prototype is measured using the free space measurement setup. The measured results show a good agreement with the simulated ones, which demonstrates the reliability of the design and fabrication. The proposed FSS with the advantages of simple structure, low cost, easy fabrication, and integration can be applied in enhancing the communication performance and anti-interference ability in the future 6G communication system.

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