Molecular Insertion: A Master Key to Unlock Smart Photoelectric Responses of Covalent Organic Frameworks

Covalent organic frameworks (COFs) show potentials in prominent photoelectric responses by judicious structural design. However, from the selections of monomers and condensation reactions to the synthesis procedures, the acquisition of photoelectric COFs has to meet overmuch high conditions, limiting the breakthrough and modulation in photoelectric responses. Herein, the study reports a creative "lock-key model" based on molecular insertion strategy. A COF with suitable cavity size, TP-TBDA, is used as the host to load guests. Merely through the volatilization of mixed solution, TP-TBDA and guests can be spontaneously assembled via non-covalent interactions (NCIs) to produce molecular-inserted COFs (MI-COFs). The NCIs between TP-TBDA and guests acted as a bridge to facilitate charge transfer in MI-COFs, unlocking the photoelectric responses of TP-TBDA. By exploiting the controllability of NCIs, the MI-COFs can realize the smart modulation of photoelectric responses by simply changing the guest molecule, thus avoiding the arduous selection of monomers and condensation reactions required by conventional COFs. The construction of molecular-inserted COFs circumvents complicated procedures for achieving performance improvement and modulation, providing a promising direction to construct late-model photoelectric responsive materials.

Suppressing the Intrinsic Photoelectric Response of Organic Semiconductors for Highly-Photostable Organic Transistors

Suppressing the photoelectric response of organic semiconductors (OSs) is of great significance for improving the operational stability of organic field-effect transistors (OFETs) in light environments, but it is quite challenging because of the great difficulty in precisely modulating exciton dynamics. In this work, photostable OFETs are demonstrated by designing the micro-structure of OSs and introducing an electrical double layer at the OS/polyelectrolyte dielectric interface, in which multiple exciton dynamic processes can be modulated. The generation and dissociation of excitons are depressed due to the small light-absorption area of the microstripe structure and the excellent crystallinity of OSs. At the same time, a highly efficient exciton quenching process is activated by the electrical double layer at the OS/polyelectrolyte dielectric interface. As a result, the OFETs show outstanding tolerance to the light irradiation of up to 306 mW·cm-2 , which far surpasses the solar irradiance value in the atmosphere (≈138 mW·cm-2 ) and achieves the highest photostability ever reported in the literature. The findings promise a general and practicable strategy for the realization of photostable OFETs and organic circuits.