Construction of TiO2/PEDOT:PSS hybrid thin films for organic solar cell: design, fabrication, characterization, and investigation

In this report, TiO2 nanoparticles (NPs) functionalized with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites films have been developed for use in organic solar cells (OSCs). The TiO2/PEDOT:PSS films were characterized by X-ray diffraction, Raman spectroscopy, UV-Vis, PL, and microscopy techniques. Atomic force microscopy (AFM) images showed that the addition of PEDOT significantly changes the morphology of the TiO2 films, with loss of uniformity and increase in surface roughness. The TiO2/PEDOT:PSS OSC showed the best performance and displayed power conversion efficiency (PCE) of 7.24%, much higher than the bare TiO2 (4.25%) OSC device. This enhanced performance is mainly driven by the improvements in the short-circuit current (similar to 16.9 mA/ cm(2)) as well as the fill factor (similar to 72%) that is ascribed to the PEDOT:PSS after incorporated with TiO2, which improved the contact between the electrolyte and electrode layer. Consequently, extraction efficiency of the photogenerated holes is increased, while recombination probability of holes and electrons in the photoactive layer is decreased. The films were further evaluated for electrochemical characterizations and the improved solar cell mechanism of the present OSCs are also discussed in details.