Construction of Large‐Area Ultrathin Conductive Metal–Organic Framework Films through Vapor‐Induced Conversion

Abstract

On account of unique characteristics, the integration of metal–organic frameworks as active materials in electronic devices attracts more and more attention. The film thickness, uniformity, area, and roughness are all fatal factors limiting the development of electrical and optoelectronic applications. However, research focused on ultrathin free‐standing films is in its infancy. Herein, a new method, vapor‐induced method, is designed to construct centimeter‐sized Ni3(HITP)2 films with well‐controlled thickness (7, 40, and 92 nm) and conductivity (0.85, 2.23, and 22.83 S m−1). Further, traditional transfer methods are tactfully applied to metal–organic graphene analogue (MOGA) films. In order to maintain the integrity of films, substrates are raised up from bottom of water to hold up films. The stripping method greatly improves the surface roughness Rq (root mean square roughness) without loss of conductivity and endows the film with excellent elasticity and flexibility. After 1000 buckling cycles, the conductance shows no obvious decrease. Therefore, the work may open up a new avenue for flexible electronic and magnetic devices based on MOGA.

Electrically Conductive Metal–Organic Frameworks

“… 17 A number of later studies reported conductivities ranging from 2.6(3) × 10 –3 to 150 S/cm for Ni 3 (HITP) 2 . 22 , 23 , 27 , 79 , 190 …”

Conductive metal‐organic frameworks: Recent advances in electrochemical energy‐related applications and perspectives

“…Similar to such methods, chemical/physical vapor deposition is another efficient method for synthesizing 2D thin films of conductive MOFs. Recently, Hu et al 53 successfully prepared the Ni 3 (HITP) 2 film by the alkaline vapor‐induced method. This method is established based on the fact that the Ni 3 (HITP) 2 shows π‐connection and involves jump transport, which is characterized by strong temperature dependence.…”

Two-dimensional conjugated metal–organic frameworks (2D c-MOFs): chemistry and function for MOFtronics

“…28,58 Meanwhile, HTTP-based MS 4 -linked (M = Ni, Co, Fe, Pt) 2D c-MOFs were also developed (mainly as films, see Section 4.2), 45,64,118 and subsequently great efforts have been devoted to the TP-based 2D c-MOF family with the aim of exploring their multifunctional properties. 28,46,59,90,100,106,109,146,147 Towards frameworks with denser distributed ligands and metals, benzene-based ligands were developed. 31,39,40,42,74,135 Typically, in 2017, Dou et al synthesized MN 4 -linked M 3 (HIB) 2 (M = Cu, Ni) 2D c-MOFs by mixing HAB, M 2+ , and NH 3 ÁH 2 O in DMSO, followed by heating at 60 1C for 2 hours.…”

“…13c). Later on, Mahringer et al explored a vapor-assisted conversion 106 as an effective way for the synthesis of face-on oriented Cu 3 (HHTP) 2 and M 9 (HHTP) 4 (M = Ni, Co) thin films on various substrates. 94 The authors utilized an additive of 1-propanol as a modulator for enlarging the crystal size (up to 10 mm for Cu 3 (HHTP) 2 , 1-2 mm for Ni 9 (HHTP) 4 , and 3-4 mm for Co 9 (HHTP) 4 ).…”