Insights into cation disorder and phase transitions in CZTS from a first-principles approach

Atomistic insights into the order–disorder transition in Cu2ZnSnS4 solar cells from Monte Carlo simulations

“…We find that the critical temperature for disordering is lowered when swaps between adjacent (001) planes are allowed. In line with recent work 37,42 , our model suggests that it is important to also consider Cu/Zn disorder on the Cu 2a sites; however, the concentration of defects in Cu-Zn planes is higher, which may explain why this is often thought to be the dominant in the order-disorder transition.…”

“…Cu/Zn disorder in 2D is believed to be the most prevalent type of substitutional disorder for near stoichiometric samples and that substitutions onto the Cu 2a sites occur only after the Cu/Zn ODT has occurred 21,24,41 . However, other studies have suggested that disorder on the 2a site plays an important role 37,42 . We therefore perform simulations to study the ODT for both cases.…”

“…Ref. 37 used a cluster expansion model with clusters out to second-nearest neighbour cations and performed MC simulations for up to 64,000 atoms. Prior to the studies outlined above, there has been little work modelling disordered phases in CZTS, apart from one study where the choice of the disordered phase was arbitrary 38 and another investigating the configurational entropy of independent microstates in small systems of up to 64 atoms 39 .…”

Element-specific investigations of ultrafast dynamics in photoexcited Cu2ZnSnS4 nanoparticles in solution

“…Full geometry optimization (including lattice vectors) with the Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional 38 and Hubbard U correction for the Cu-d states 39 was performed with a U value of 6.0 eV in correspondence with previous studies. 40 A bandgap of 0.6566 eV was obtained, which corresponds to an offset of 0.82 eV with respect to the above HSE calculation. All possible excitations of one electron from the valence to the conduction band that fall within an energy difference no greater than 3.1 − 0.82 = 2.3 eV were considered through a Delta Self-Consistent Field Δ(SCF) approach, in which the excited state is calculated by enforcing the corresponding non-Aufbau occupation of the bands.…”

High-pressure behavior of disordered kesterite-type Cu2ZnSnS4

“…Partly motivated by our aforementioned high-pressure studies on the KS modification, and given that in the majority of synthetic Cu 2 ZnSnS 4 samples the Cu/Zn disorder is always present to some extent [24][25][26], we have investigated the pressure-induced structural and vibrational behavior of the DKS Cu 2 ZnSnS 4 compound by means of X-ray diffraction (XRD), Raman spectroscopy, and density functional theory (DFT) calculations. Similar to KS, DKS Cu 2 ZnSnS 4 undergoes a pressure-induced DKS → GeSb-type structural transition close to 15 GPa, with a disordered ZB-type structure being recovered upon full decompression [20].…”