Investigation of pressure-induced phase transitions of the solar cell materials CdSe1−xTex alloys: one- and two-dimensional search DFT calculation

Abstract

ABSTRACTGibbs script within the all-electron full potential linearized augmented plane wave (FP-LAPW) method has been used to calculate pressure-induced phase transition at zero temperature for selected phases. The calculation exhibits that CdSe is stable at wurtzite phase whereas CdSe0.75Te0.25, CdSe0.5Te0.5, CdSe0.25Te0.75 and CdTe are stable at cubic phase. This prediction is consistent with experimental work of Schenk and Silber at ˂ 800 °C except for CdSe0.75Te0.25. We found that increasing the Te content for both phases of ternary CdSe1−xTex alloys decreases the optimized energy and bulk modulus, hence leads to decrease hardness, while it increases the optimized volume. The density functional theory (DFT) calculation within generalized gradient approximation (PBE-GGA) and the two-dimensional search of equation of state for wurtzite phase predict a possible pressure-induced phase transition from cubic to wurtzite phase for the ternary CdSe0.5Te0.5, CdSe0.75Te0.25 and CdTe at pressures of about 13.6, 1.9 and 10.6 (GPa) with corresponding volume collapses at the phase-transition boundary of about 181.115 and 180.525, 203.839 and 203.485 and 203.337 and 202.692 (bohr3/atom), respectively. However, one-dimensional search of equation of state for wurtzite phases predicts a possible pressure-induced phase transition at pressures 14.5, 1.9 and 11.4 for CdSe0.5Te0.5, CdSe0.75Te0.25 and CdTe, respectively.