Two-Dimensional AMgB (A = Na, K; B = P, As, Sb, Bi) with Promising Optoelectronic and Thermoelectric Performances

For the purpose of solar energy harvesting, we have predicted eight kinds of stable two-dimensional materials: AMgB (A = Na, K; B = P, As, Sb, Bi) based on first-principles calculations. The band gaps of AMgB monolayers (MLs for short) cover a wide range from 0.39 to 1.68 eV and all exhibit direct or quasi-direct band features. More encouragingly, AMgB MLs possess high acoustic phonon-limited carrier mobilities ranging from 103 to 107 cm2 V–1 s–1. In addition, noticeable optical absorption from the visible light to ultraviolet regimes has been predicted for AMgB MLs and the power conversion efficiencies (PCEs) are up to 22.06 and 16.26% for the proposed NaMgAs/NaMgSb and KMgP/KMgAs type-II heterojunctions. Moreover, combined with low thermal conductivity and fairly large power factor, considerable thermoelectric properties have been theoretically confirmed in AMgB MLs with the figure of merit (ZT) up to 1.15 (NaMgBi ML). Desired band gap, ultrahigh carrier mobility, excellent light absorption capacity, and high ZT values could render AMgB MLs promising candidates for low-dimensional optoelectronic and thermoelectric applications.