In recent years, perovskite solar cells have been considerably developed, however the lead in the absorber MAPbI3 is a potential threat to the environment. To explore potential alternatives, the structural and electronic properties of MAGeX3 (X = Cl, Br, I) were investigated using different density functional theory methods, including GGA-PBE, PBE-SOC, HSE06 and HSE-SOC. The results implied that MAGeI3 exhibits an analogous band gap, substantial stability, remarkable optical properties, and significant hole and electron conductive behavior compared with the so far widely used absorber MAPbI3. Moreover, the calculations revealed that the energy splitting resulting from the spin-orbit coupling is evident on Pb, moderate on Ge, I and Br, and negligible on Cl. Our work not only sheds some light on screening novel absorbers for perovskite solar cells but also deepens the understanding of these functional materials.

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Carbides represent a class of functional materials with unique properties and increasing importance. However, the harsh conditions in conventional synthetic strategies impede subtle control over size and morphology of carbides, which is highly imperative for their practical applications. Herein, we report a facile, simple approach to prepare porous Co3ZnC/N-doped carbon hybrid nanospheres. In this structure, the Co3ZnC nanoparticles exhibit a core-shell structure and they are uniformly confined in N-doped carbon conductive networks forming rather uniform nanospheres. The hybrid nanospheres have a specific surface area as high as 170.5 m(2) g(-1). When evaluated as an anode material for lithium ion batteries, they show an excellent lithium storage performance, which can be attributed to the combined effect of the core-shell Co3ZnC nanoparticles, the pore structure and the highly conductive and elastic N-doped carbon networks. This work provides an efficient route for the facile production of nanoscale carbides with desirable manipulation over size and morphology for many of important applications.

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