High Stability, Piezoelectric Response, and Promising Photocatalytic Activity on the New Pentagonal CGeP4 Monolayer

This study introduces the penta-structured semiconductor p-CGeP₄ through density functional theory simulations, which possesses an indirect band gap transition of 3.20 eV. Mechanical analysis confirms the mechanical stability of p-CGeP₄, satisfying Born–Huang criteria. Notably, p-CGeP₄ has significant direct (e₃₁ = −11.27 and e₃₆ = −5.34 × 10^–10 C/m) and converse (d₃₁ = −18.52 and d₃₆ = −13.18 pm/V) piezoelectric coefficients, surpassing other pentagon-based structures. Under tensile strain, the band gap energy increases to 3.31 eV at 4% strain, then decreases smoothly to 1.97 eV at maximum stretching, representing an ∼38% variation. Under compressive strain, the band gap decreases almost linearly to 2.65 eV at −8% strain and then drops sharply to 0.97 eV, an ∼69% variation. Strongly basic conditions result in a promising band alignment for the new p-CGeP₄ monolayer. This suggests potential photocatalytic behavior across all tensile strain regimes and significant compression levels (ε = 0% to −8%). This study highlights the potential of p-CGeP₄ for groundbreaking applications in nanoelectronic devices and materials engineering.