Al2B12C with High Ambipolar Mobility Driven by a Unique B-C Framework.

Abstract

The development of materials with high ambipolar mobility is pivotal for advancing multifunctional applications, yet such materials remain scarce. Presently, cubic boron arsenide (BAs) stands out as the premier ambipolar material, demonstrating an ambipolar mobility of ∼1600 cm2 V-1 s-1 at room temperature [Science 2022, 377, 433 and Science 2022, 377, 437]. Herein, we illustrate that semiconducting Al2B12C, featuring a nonclathrate B-C framework in which a C atom bonds to the vertices of four distorted hexagonal antiprism B12 units via quasi-sp3 hybridization, is predicted to possess ambipolar carrier transport behavior. Its ambipolar mobility can reach up to ∼2095 cm2 V-1 s-1. The hole transport originates from the C pz orbitals that trap the electrons of Al atoms at the valence band maximum, forming a C-Al-C hole channel along the c-axis direction, whereas electron transport stems from the π electrons in B12 units. For Al2B12C, polar optical phonon scattering serves as the primary mechanism limiting mobility. Additionally, it displays a high absorption coefficient (105 cm-1) in the visible spectrum. These appealing properties make Al2B12C a highly promising environmentally friendly semiconductor for applications in electronics and photovoltaic devices.