How Thermodynamically Accessible are Quaternary Mixed-Metal Chalcohalides?

Pascal Henkel; G. Krishnamurthy Grandhi; Jarno Laakso; David Rovira Ferrer; Edgardo Saucedo; Jingrui Li; Paola Vivo; Miguel A. L. Marques; Patrick Rinke

paper

How Thermodynamically Accessible are Quaternary Mixed-Metal Chalcohalides?

arXiv:2609.38125

Abstract

Quaternary mixed-metal chalcohalides (MMCHs) are a promising mixed-anion semiconductor family, but their thermodynamic accessibility remains largely unexplored. We combine density functional theory with the Alexandria Materials Database to carry out a rapid and reliable evaluation of the thermodynamic accessibility of 54 M(II) $_{2}$ M(III)Ch $_{2}$ X $_{3}$ compounds. All evaluated MMCHs are predicted to be thermodynamically unstable, but a considerable fraction of MMCHs lie within computational uncertainty of the convex hull. Their predicted decomposition follows five distinct reaction pathways, most commonly into M(III) $_{2}$ Ch $_{3}$ , M(II)X $_{2}$ , and M(II)Ch. Solution processing of six Sn-based MMCHs supports our analysis. Notably, this includes the first synthesis of the previously unreported Sn $_{2}$ InS $_{2}$ Br $_{3}$ in a multiphase film. Our approach identifies convex hull proximity and competing phase formation as key constraints on MMCH synthetic accessibility during solution processing, thereby guiding future MMCH exploration.