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

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 [<i>Science</i> 2022, 377, 433 and <i>Science</i> 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 p_<i>z</i> orbitals that trap the electrons of Al atoms at the valence band maximum, forming a C-Al-C hole channel along the <i>c</i>-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.