Jinxin Liu

2D Conjugated Metal–Organic Frameworks towards Monolithic 3D Integration

Three-dimensional monolithic integration technology based on the vertical stacking of two-dimensional materials provides a new pathway to break through the development bottlenecks of traditional planar integrated circuits. It is expected to increase device integration density while reducing interconnect delay and power consumption, and further expand multifunctional integration capabilities beyond the scaling limits of Moore's Law. However, the key to realizing the industrial application of this technology lies in how to achieve controllable, wafer-scale preparation of high-quality two-dimensional active materials under a low thermal budget (<400 °C). For the widely studied inorganic two-dimensional materials, such as MoS2, graphene, and hexagonal boron nitride (h-BN), their lattice structures are mainly composed of relatively strong covalent bonds, which typically require higher growth temperatures to overcome reaction energy barriers and promote reversible bond breaking and formation in order to achieve high crystalline quality. Therefore, achieving controllable preparation of high-quality, large-area inorganic two-dimensional materials at low temperatures still faces significant challenges.

In contrast, two-dimensional conjugated metal-organic frameworks (2D c-MOFs) are constructed through coordination interactions between π-conjugated organic ligands and metal nodes. Their formation process is thermodynamically favorable and generally has lower reaction kinetic energy barriers, enabling controllable preparation at relatively low temperatures (typically <200 °C). At the same time, the unique in-plane π–d conjugated structure endows such materials with rich and tunable charge transport properties, making them a potential material system for achieving low-temperature, multifunctional three-dimensional monolithic integration.

This report will introduce our research progress in establishing a chemical vapor deposition (CVD) preparation method for two-dimensional conjugated metal-organic frameworks, with a focus on demonstrating how a scalable vapor-phase growth strategy can achieve the preparation of large-area 2D c-MOF thin films with good crystalline quality, ultra-flat surfaces, and high uniformity. On this basis, we will further discuss the direct integration of vapor-phase-grown thin films with existing electronic device platforms, demonstrate their applications in electronic and optoelectronic devices such as high-performance photodetectors, and elucidate the structure-property relationships among material crystal structure, electronic properties, and device performance, thereby providing new ideas for the design of 2D c-MOF functional electronic units for low-temperature three-dimensional monolithic integration.