Electronic Structures And Optical Properties Of Cubic Crystal K2cssb, K3sb And Cs3sb Cathode Materials

Considering the possible existence of three types of compounds, namely K3Sb, K2CsSb and Cs-3 Sb in the growth of K2CsSb photocathode, a first-principles study based on density functional theory was employed to establish the cubic bulk models and the (111) surface models for the three types of antimonide cathode materials. Through theoretical calculations, electronic structures and optical properties were obtained, wherein band structures, densities of states and optical properties were acquired for bulk models, and work function, optical properties and surface energy were calculated for (111) surface models. The results demonstrate that, as for the three types of antimonide cathodes, in the radiation energy range of 2.4 similar to 3.2 eV produced by interaction between neutrinos and scintillators, the absorption and relectivity of K2CsSb bulk material are close to those of Cs3Sb and K3Sb ones, whereas the values of K2CsSb (111) surface material are lower than those of Cs3Sb and K3Sb ones. In addition, K3Sb has the narrowest bandgap, maximum work function and maximum surface energy, while Cs3Sb has the minimum surface energy and its work function is close to that of K2CsSb, but its band gap is smaller than that of K2CsSb. By contrast, K2CsSb with the widest bandgap has the smaller work function and surface energy. Therefore, K2CsSb photocathode is suitable to serve as a stable and high-efficient photoemitter in the blue-violet spectral region.