Prediction of Novel p-Type Transparent Conductors in Layered Double Perovskites: A First-Principles Study

The development of high-performance transparent conductors (TCs) is critical to various technologies from transparent electronics to solar cells. Whereas n-type TCs have been extensively applied in many electronic devices, their p-type counterparts have not been largely commercialized due to the lack of ideal materials. Combining atomic replacement and first-principles calculations, seven stable layered double perovskites are identified, i.e., Cs₄CuSb₂Cl₁₂-like Cs₄M²⁺B³⁺ ₂X^VII ₁₂ compounds as promising p-type TCs with sufficiently large bandgaps, delocalized wavefunction distribution with s-orbital components in valence band maximum (VBM) and the antibonding character of VBM to ensure their optical transparency, light hole effective masses, and intrinsic good p-type conductivities, respectively. Taking Cs₄CdSb₂Cl₁₂ as a representative example, it is demonstrated that under Cd-poor (Cl-rich) conditions, Cs₄CdSb₂Cl₁₂ could exhibit excellent p-type conductivity with high hole concentration, contributed by the intrinsic shallow-acceptor Cd_Sb with extremely low formation energy. Generally, the other 6 Cs₄M²⁺B³⁺ ₂X^VII ₁₂ compounds exhibit similar intrinsic p-type defect properties as Cs₄CdSb₂Cl₁₂, which could rank them as the top p-type TCs discovered or predicted until now.