Prediction of two-dimensional C3N2 semiconductors with outstanding stability, moderate band gaps, and high carrier mobility.

Abstract

Two-dimensional (2D) semiconductors with suitable band gaps, high carrier mobility, and environmental stability are crucial for applications in the next generation of electronics and optoelectronics. However, current candidate materials each have one or more issues. In this work, two novel C3N2 monolayers, P-C3N2 and I-C3N2 are proposed by first-principles calculations. Both structures have demonstrated excellent dynamical and mechanical stability, with thermal stability approaching 3000 K. Importantly, P-C3N2 shows a distinct advantage in formation energy compared to currently synthesized 2D carbon nitride materials, indicating its potential for experimental synthesis. Electronic structure calculations reveal that both P-C3N2 and I-C3N2 are intrinsic semiconductors with moderate band gaps of 2.19 and 1.81 eV, respectively. Additionally, both C3N2 monolayers display high absorption coefficients up to 105 cm-1, with P-C3N2 showing significant absorption capabilities in the visible light region. Remarkably, P-C3N2 possesses an ultra-high carrier mobility of up to 104 cm2 V-1 s-1. These findings provide theoretical insights and candidates for future applications in the electronics and optoelectronics fields.