RESEARCH ARTICLE Extensive investigation of structural, electronic, optical, and thermoelectric properties of hybrid perovskite (CH 3 NH 3 PbBr 3 ) with mechanical stability constants Shaily Choudhary | Akash Shukla | Jyoti Chaudhary | Ajay Singh Verma Department of Physics, Banasthali Vidyapith, Banasthali, 304022, India Correspondence Ajay Singh Verma, Department of Physics, Banasthali Vidyapith, Banasthali, Rajasthan 304022, India. Email: ajay_phy@rediffmail.com Summary Recently, Organometallic halide based perovskites have emanated as an auspi- cious candidate as a solar cell absorber layer. In this article, we have explored the fundamental properties such as structural, electronic, optical, elastic, and thermoelectric parameters of CH 3 NH 3 PbBr 3 through first-principles calcula- tions, because it has accomplished the entire criterion to use in photovoltaic and thermoelectric applications. We have used full-potential linearized augmented plane wave method (FP-LAPW) within DFT and implemented in Wien2k. The generalized gradient approximation (GGA) parameterized by Wu-Cohen (WC) has been used to optimize the lattice parameter, while for band gap calcu- lations different exchange-correlation potentials (LDA/GGA) have been used. The band gap up to 2.26 eV has been achieved by doing some appropriate changes in the parameter of TB-mBJ exchange-correlation potential. The nature of band gap is direct and exist at R (0.5 0.5 0.5) symmetry point of the Brillouin zone. All the optical spectral response between 2 and 5 eV is due to the transi- tion of Br 5p with little contribution Pb 5s orbital electrons of VBM to Pb 6p orbitals in CBM and a minor contribution of second band gap components also incorporate. As well as, a high absorption coefficient shows that it may be strongly applied in photovoltaic devices. The orientation of organic cations (CH 3 NH 3 ) + has no considerable impact on the band structure formation. To render a solid foundation about the application in the thermoelectric device up to the high-temperature region, the thermoelectric parameters have been dis- cussed at optimal carrier concentration and definite temperature range. The measurement of elastic constants, B/G and Poisson's ratio indicates the ductile nature of CH 3 NH 3 PbBr 3 . To the best of my knowledge, most of the investiga- tions have been discussed first time for this material. KEYWORDS absorption coefficient, band gap, dielectric constant, elastic constants, figure of merit, Seebeck coefficient JEL CLASSIFICATION 71.15.Mb; 71.20.-b; 73.50.Lw; 78.20.Ci; 81.05.Hd; 81.07.Pr Received: 30 April 2020 Revised: 30 June 2020 Accepted: 4 July 2020 DOI: 10.1002/er.5786 Int J Energy Res. 2020;1–15. wileyonlinelibrary.com/journal/er © 2020 John Wiley & Sons Ltd 1