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Addressing the critical scarcity of $p$-type transparent conducting materials for optoelectronics, the authors executed a high-throughput computational search across ternary X–Cu–I compositional spaces. Combining the minima hopping global structure search with density functional theory, the screen uncovered 58 candidate conductors—49 previously unreported—including 20 degenerate semiconductors such as Cu$_2$FI$_2$ featuring a 3.75 eV bandgap and an ultralow hole effective mass of $0.262\,m_0$. Analysis of the resulting dataset fundamentally updates the chemical modulation of the valence band framework, establishing that tetrahedral Cu coordination, I $5p$ hybridization, and the Cu $d$-state energy center reliably govern $p$-type halide design.
Forty-nine newly discovered $p$-type transparent conductors upend decades-old delafossite design rules, proving that tetrahedral Cu coordination and iodide hybridization unlock ultra-low hole effective masses without sacrificing optical transparency.
P-type transparent conducting materials (TCMs) remain scarce, limiting progress in transparent electronics and tandem photovoltaics. Here, we perform a high-throughput computational search across CuI-based ternary X--Cu--I compounds using the minima hopping method combined with density functional theory. Filtering for thermodynamic stability, optical transparency, and light hole effective mass, we identify 58 candidate p-type TCMs, of which 49 are previously unreported. Twenty are p-type degenerate semiconductors with intrinsic hole carriers, including Cu$_2$FI$_2$ (calculated gap 3.75 eV, hole effective mass $0.262\,m_0$). We further use this dataset to revisit the chemical modulation of the valence band (CMVB) design rules, originally formulated for Cu-based delafossite oxides. Four generalizations emerge: linear Cu coordination is not required, as tetrahedral coordination (CN = 4) is compatible with p-type TCM character; the mechanism extends to halide-based systems with I $5p$ anion states; the Cu $d$ state energy center $\epsilon_d$ is a quantitative descriptor for valence band dispersion; and Cu undercoordination in monovalent-anion hosts drives intrinsic p-type carrier generation through stoichiometric charge balance. These results establish a generalized computational framework for the design of p-type halide TCMs.