Computational exploration of energy materials: the Zn–As–P ternary phase diagram

Abstract We present a comprehensive ab initio investigation of the thermodynamic stability and electronic properties of the earth-abundant Zn–As–P ternary system. Through density functional theory we identified four stable binary compounds: Zn 3 As 2 , Zn 3 P 2 , ZnAs 2 , and ZnP 2 , but no stable ternary compounds. Nevertheless, ordered ternary alloys of the form Zn 3 (As x P <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi/> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>−</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) 2 exhibit formation energies within a few <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mrow> <mml:mi>meV</mml:mi> </mml:mrow> </mml:mrow> </mml:math> atom −1 of the convex hull, indicating the potential for thermodynamic stabilization of disordered solid solutions at finite temperature through configurational entropy effects, in agreement with previous experimental work. Our computed band gaps for these ternary alloys demonstrate tunable electronic properties across the composition range. Further transport calculations reveal promising Seebeck coefficients and electrical conductivities for Zn 3 (As x P <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi/> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>−</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) 2 alloys, highlighting their potential for thermoelectric and photovoltaic applications.