Quasiparticle GW Calculations on Lead-Free Hybrid Germanium Iodide Perovskite CH3NH3GeI3 for Photovoltaic Applications

Deivasigamani Umadevi; Graeme W Watson

doi:10.1021/acsomega.8b03291

Quasiparticle GW Calculations on Lead-Free Hybrid Germanium Iodide Perovskite CH₃NH₃GeI₃ for Photovoltaic Applications

ACS Omega. 2019 Mar 21;4(3):5661-5669. doi: 10.1021/acsomega.8b03291. eCollection 2019 Mar 31.

Authors

Deivasigamani Umadevi¹, Graeme W Watson¹

Affiliation

¹ School of Chemistry and CRANN, Trinity College Dublin, The University of Dublin, Dublin D2, Ireland.

Abstract

Lead-free organic-inorganic halide perovskites have gained much attention as nontoxic alternatives to CH₃NH₃PbI₃ in next-generation solar cells. In this study, we have examined the geometric and electronic properties of methylammonium germanium iodide CH₃NH₃GeI₃ using density functional theory. Identifying a suitable functional to accurately model the germanium halide perovskites is crucial to allow the theoretical investigation for tuning the optoelectronic properties. The performance of various functionals (PBE, PBE+D3, PBEsol, PBEsol+D3, HSE06, and HSE06+D3) has been evaluated for modelling the structure and properties. The calculation of electronic properties was further refined by using the quasiparticle GW method on the optimized geometries, and that has an excellent agreement with the experiment. We report from our GW calculations that the characteristic of the density of states for CH₃NH₃GeI₃ resembles the density of states for CH₃NH₃PbI₃ and the effective masses of the charge carriers of CH₃NH₃GeI₃ are comparable to the effective masses of CH₃NH₃PbI₃ as well as silicon used in commercially available solar cells.