Lead Chloride Perovskite Variant Cs ₂ PbCl ₆ as an <i>n</i> -Type Transparent Semiconductor: A First-Principles Prediction

Transparent semiconductors with tunable conductivity and wide bandgaps are essential for modern optoelectronics. While lead halide perovskites have demonstrated outstanding performance in devices such as solar cells and light-emitting diodes, their potential as <i>n</i>-type transparent semiconductors remains underexplored. Herein, we employ first-principles calculations to identify the vacancy-ordered perovskite variant Cs₂PbCl₆ as a candidate for such applications. Our findings show that Cs₂PbCl₆ possesses an optical bandgap of ∼2.9 eV and a conduction band minimum at approximately -4.6 eV, meeting the empirical threshold for efficient <i>n</i>-type doping. Defect analysis reveals that key intrinsic defects, including Cl vacancies, Pb interstitials, and Cs interstitials, act as shallow donors; however, their electron donation is partially compensated by Cs vacancy acceptors even under the chlorine-poor condition, leading to weak <i>n</i>-type conductivity at room temperature. By elevating the growth temperature to 500 K and introducing extrinsic dopants such as interstitial Na and K, the electron concentration can be increased to ∼10¹⁶ cm^-3, enabling Cs₂PbCl₆ to serve as a low-temperature-processable <i>n</i>-type transparent semiconductor. This work thereby provides a theoretical foundation for this material system and establishes a framework for the rational design of halide perovskite-based transparent semiconductors.