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: A Mg B ( A = Na, K; B = P, As, Sb, Bi) based on first-principles calculations. The band gaps of A Mg B 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, A Mg B MLs possess high acoustic phonon-limited carrier mobilities ranging from 10 3 to 10 7 cm 2 V –1 s –1 . In addition, noticeable optical absorption from the visible light to ultraviolet regimes has been predicted for A Mg B 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 A Mg B 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 A Mg B MLs promising candidates for low-dimensional optoelectronic and thermoelectric applications.