Improving P3HT:PCBM absorber layers by blending TiO2/CdS nanocomposites for application in photovoltaic solar cells

• Published in: Journal of materials science. Materials in electronics Vol. 32; no. 1; pp. 102 - 112
• Main Authors: Oviedo-Mendoza, M., Zapata-Torres, M., Meléndez-Lira, M., Mis-Fernández, R., Peña, J. L., Hernández-Rodríguez, E.
• Format: Journal Article
• Language: English
• Published: New York Springer US 2021; Springer Nature B.V
• Subjects: Absorbers; Anatase; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal structure; Crystallinity; Electrical properties; Electrical resistivity; Electromagnetic absorption; Materials Science; Nanocomposites; Nanocrystals; Optical and Electronic Materials; Optical properties; Photovoltaic cells; Solar cells; Titanium dioxide; X ray photoelectron spectroscopy
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-020-04705-9

In this work we propose the use of the semiconducting TiO 2 /CdS nanocomposite (NC) to improve the optical and electrical properties of the P3HT:PCBM polymeric system employed as the absorber layer in organic photovoltaic solar cells. Therefore, we report a methodology for obtaining the TiO 2 /CdS-NC, its incorporation into precursor solutions containing P3HT and PCBM polymers, and the fabrication of hybrid P3HT:PCBM:TiO 2 /CdS-NC absorber layers. The effect of the mass ratio between the TiO 2 /CdS-NC and the polymeric system was studied. XRD measurements conducted on the TiO 2 /CdS-NC showed that the TiO 2 component has a tetragonal crystalline structure (anatase phase) with a nanocrystalline size of 15.8 nm, while the CdS component has the hexagonal close-packed crystalline structure with a nanocrystalline size of 14.9 nm. XPS analysis confirmed the formation of stoichiometric TiO 2 and CdS compounds. The formation of any other compound comprising the elements Ti, O, Cd and S was not found, however, elements Cl, Br, N and C were observed at trace levels, which come from the capping agent that was used to obtain the nanocomposite. Measurements on the hybrid P3HT:PCBM:TiO 2 /CdS-NC absorber layers through UV-vis spectroscopy showed a shift on the absorption edge and an improved light absorption for wavelengths below 550 nm. The four-point probe measurements showed a decrease of the electrical resistivity from 8.5 × 10 8 Ω-cm in pristine P3HT:PCBM to a minimum of 4 × 10 5 Ω-cm in the hybrid absorber layers. Both the light absorption and the electrical resistivity are modulated by the mass ratio between the TiO 2 /CdS-NC and the P3HT:PCBM polymeric system.