Two novel highly efficient and low-cost phenothiazine 5,5-dioxide core building block based hole transport materials are reported, achieving a power conversion efficiency as high as 20.2%.

The direct bandgap nature of semiconductors is crucial for a wide range of optoelectronic devices and energy applications. These materials are mainly concentrated in hybrid organic–inorganic halide perovskites, III–V semiconductors, and monolayer transition metal dichalcogenides. Here, we report an AA′3B2B′2O12-type direct bandgap semiconductor CaCu3Fe2Ta2O12 using spin-polarized density functional theory calculations. The formation energy indicates that this material is thermodynamically preferred under a high-temperature and high-pressure synthetic route, similar to the analog CaCu3Fe2Nb2O12. Effective ferrimagnetic interaction occurs through the antiferromagnetic coupling between the A-site Cu and B-site Fe. More importantly, CaCu3Fe2Ta2O12 exhibits semiconducting behavior with a direct bandgap in the visible range, suggesting that AA′3B2B′2O12-type quadruple perovskites are potential candidate materials in photovoltaics as well as in optoelectronic devices.

Half-metals have drawn extensive interest due to their unique electronic structure and wide application in spintronics. We report an A-site-ordered quadruple perovskite CeCu3Cr4O12 with half-metallic behaviors using first-principles calculations. Our calculations demonstrate that CeCu3Cr4O12 is a ferrimagnet with a saturated magnetic moment of 7.00 μB f.u.–1. Effective ferrimagnetic interactions are generated from the antiparallel spin arrangement between the A′-site Cu and B-site Cr. The electronic structure analyses reveal that CeCu3Cr4O12 exhibits half-metal performance, which can be attributed to the mixed-valence of B-site Cr. More importantly, a small amount of 4f itinerant electrons are located on the A-site Ce, i.e., both itinerant electron magnetism and localized magnetic moments are observed in the theoretical calculations. The charge distribution in this system is confirmed to be Ce(4−δ)+Cu2+3Cr(3.5+δ)+4O2−12. The physical properties of the AA′3B4O12-type perovskite CeCu3Cr4O12 revealed in this study show that this class of materials shows promise in applications of half-metals.