Study of Tl-based perovskite materials TlZX3 (Z = Ge, Sn, Be, Sr; X = Cl, Br, I) for application in scintillators: DFT and TD-DFT approach

Scintillators are designed significantly for utilization in a broad range of technology fields, notably nuclear physics, healthcare testing, and materials analysis. A number of applications involving scintillators, such as therapeutic image analysis, burglary prevention as well and nuclear investigation, have tempted scientists to establish novel and effective scintillators. In this report, thallium-based perovskite material TlZX3 (Z = Ge, Sn, Be, Sr; X = Cl, Br, I) has been examined by means of DFT and TD-DFT approaches. The structural, electronic, optical, and thermal properties of TlZX3 are calculated and discussed. The HOMO-LUMO energy gap of TlGeX3, TlSnX3, TlBeX3, and TlSrX3 are found in the range of 1.76 eV to 2.12 eV, 1.77 eV to 2.27 eV, 1.56 eV to 2.04 eV and 1.06 eV to 2.81 eV, respectively. Lattice constant, unit cell volume, formation energy, VEA, electrophilicity index, polarizability, refractive index, dielectric constant, entropy, and heat capacity of TlZX3 increase gradually from Cl to Br to I. However, HOMO-LUMO energy gap, tolerance factor, dipole moment, optical electronegativity, thermal energy, ZVPE, and Gibbs energy drop down from Cl to Br to I. Among the studied materials, TlGeI3 shows the maximum value of molecular hardness and electronegativity while TlSrCl3 exhibits the minimum value. The computed HOMO-LUMO energy gap and refractive index of the studied materials are in close agreement with the previously reported findings, it specifies their potential application in scintillator and solar cells.