Selective Growth of Covalent Organic Framework Ultrathin Films on Hexagonal Boron Nitride

Incorporating the intriguing covalent organic framework (COF) into devices and performing their advanced electronic nature are still challenging. Herein, we demonstrate the direct growth of 2D full-conjugated COF ultrathin films on dielectric hexagonal boron nitride (hBN) for the first time and study the carrier transporting characteristics of π-conjugated COF films. Under the optimized solvothermal conditions, few-layered COF-366 films with the covalent connection of tetra(p-aminophenyl)porphyrin and terephthalaldehyde are selectively fabricated on mechanically exfoliated hBN flakes. COF-366 films on hBN substrate present red-shift absorption edge and decreased band gap compared to the bulk COF powders. The organic field-effect transistor device based on COF-366 ultrathin films demonstrates p-type current modulation with an on/off ratio of 105 and mobility of 0.015 cm2 V–1 s–1. The present work represents a universal method for COF film growth on dielectric surface and also provides important insight into the carrier transport of 2D π-conjugated system and potential applications of 2D COFs in electronics.