The adhesive energies between Poly(3‐hexylthiophene) and Polyvinylpyrrolidone for organic electronic devices: Hybrid‐exchange density‐functional‐theory studies

Studying the building blocks for organic electronics-molecules-is important for achieving a great performance for organic electronic devices. Poly(3-hexylthiophene) (P3HT) and povidone (PVP) are common molecules chosen for the semiconducting and dielectric layers of organic electronic devices, respectively. Here, we have applied the hybrid-exchange density-functional theory, taking into account empirical dispersion forces and basis set superposition errors, to study the adhesive energies and optimal geometries when integrating the two types of molecules. To ease the analysis of the molecular structures, we have simplified the polymer chain structure to the monomer, dimer and trimer for the P3HT and PVP. By using B3LYP and BLYP functionals in combination with dispersion forces, we have found that the optimal inter-molecular vertical distances between P3HT and PVP are approximately 3.6, 6 and 5 angstrom for monomer, dimer and trimer, respectively, with the lowest adsorption energy of similar to-0.35, -0.15 and -0.45 eV. However, the sliding effect for the molecular combination is relatively small. These computational results can be potentially compared with the relevant experiments on the molecular crystal structure. The molecular orbitals of the P3HT and PVP molecules show that the charge density is mainly on the five-member rings rather than the polymer chains, which further supports our finite-chain approximation. Our calculations, especially the potential curves, could be useful for the optimal design of molecular structures for organic electronic devices.