DFT insights into the electronic, optical, and interfacial properties of SrTiO3-modified polytetracyanomethane hybrid semiconductors

Heterojunctions between polymer and inorganic semiconductors have attracted considerable interest owing to their unique tunable electrical and optical properties and potential applications in optoelectronics and photochemistry. In this work, the structural, electronic, interfacial, and optical properties of a heterojunction between SrTiO3 and poly(tetracyanomethane) (PTCM) were studied using density functional theory (DFT) calculations with the GGA-PBE approximation. It was found that there exists a stable interface with strong Ti–N bond formation and good interfacial interaction. The electronic band structure showed a decreased band gap of approximately 1.85 eV compared with bulk SrTiO3, with a type-II band alignment that favors effective charge separation and suppresses electron hole pair recombination. DOS and PDOS analysis suggested a strong orbital interaction between Ti 3d and N/C 2p orbitals near the Fermi level, which leads to interfacial charge transfer. Moreover, from optical studies, it was shown that the SrTiO3/PTCM interface had enhanced dielectric response, better visible light absorption, favorable refractive index, lower reflectance, and optical conductivity, thus showing higher photon absorption capacity. In addition, energy loss functions indicated better electron excitation with high-energy photons.

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