Classification of MAOX phases and semiconductor screening for next-generation energy conversion ceramic materials†
MAOX semiconductors, a family of layered oxycarbides, have recently been discovered [Z. Wang, X. Chen and C. Niu, J. Phys. Chem. C, 2018, 122, 14240–14247]. Spectroscopic limited maximum efficiency (SLME) calculations show that MAOX semiconductors can have fantastic theoretical efficiencies. In particular, four MAOX semiconductors, La2CdS2C, La2HgS2C, Cr2MgO2C, and Cr2ZnO2C, are identified to be excellent solar absorbers with maximum efficiencies of 30% and above. To classify 2121 MAOX phases and screen semiconductors, a computational screening scheme is proposed. The SLME, a/c ratio, electron affinity (EA) and ionization potential (IP)/work function (WF) are found to be good descriptors for the design of MAOX absorber layers. Linear relationships are found between the a/c ratios and fundamental bandgaps with fixed M and O. The electronic properties of MAOX can be easily tuned with different metal cations and chalcogen anions. Additionally, the band alignment of MAOX is determined by A's EA and WF.