Preparation and photoelectric properties of organoinorganic polymer nanocomposites on the basis of ultradispersed molybdenum disulfide particles

Photoconducting nanocomposites were prepared by incorporating nanoparticles obtained by monolayer dispersion of crystalline molybdenum disulfide into various polymer matrices (nonconducting and p-or n-type conducting). The shift of the absorption spectrum caused by changes in the concentration of MoS₂ nanoparticles demonstrated that such particles exhibit a quantum-size effect, the characteristics of which were found to be determined by the efficiency of their stabilization in each of the polymer matrices. Studying the photoelectric sensitivity of films of n-type-conduction composites on the basis of polymethylphenylsiloxane modified with 2,4,7-trinitrofluorenone (an electron acceptor) units demonstrated that molybdenum disulfide nanoparticles possess acceptor properties (characterized by an electron affinity energy of E _a > 2 eV, in agreement with the observation that composite films based on poly(N-epoxypropylcarbazole (a p-type-conduction matrix) doped with p-diethylaminobenzaldehyde-N,N-diphenylhydrazone (an effective donor), exhibit an enhancement in the proper photosensitivity of the p-type-conduction matrix in its absorption band (λ < 400 nm). For large molybdenum disulfide particles capable of absorbing light with λ > 600 nm (formed at a MoS₂ concentration of > 2.0 wt %), a weakening of the acceptor properties was observed, a feature responsible for decreases in the photosensitivity and the quantum yield of the photogeneration of holes and for the capture of holes in traps. A mechanism of the photogeneration of charge carriers with the participation of the phototransfer of electrons leading to the formation of electron-hole pairs was discussed.