Soluble transition metal oxide/polymeric acid composites for efficient hole-transport layers in polymer solar cells
Junghwan Kim1, Heejoo Kim, Geunjin Kim
1Department of Nanobio Materials and Electronics, ‡Heeger Center for Advanced Materials & Research Institute for Solar and Sustainable Energies, §School of Materials Science and Engineering, Gwangju Institute of Science and Technology , Gwangju 500-712, Republic of Korea.
Abstract:
We report a new method for developing a low-temperature solution processed vanadium oxide (s-VOx) and poly(4-styrene sulfonic acid) (PSS) composite to act as an efficient hole-transport layer (HTL) in polymer solar cells (PSCs). By compositing the s-VOx and PSS (s-VOx:PSS), the work function values of the s-VOx:PSS changed from 5.0 to 5.3 eV. Therefore, the energy level barrier between the HTL and organic active layer decreased, facilitating charge injection/extraction at the interfaces. In addition, the s-VOx:PSS films were denser and had more pin-hole-free surfaces than pristine s-VOx films, resulting in enhanced PSC performance due to significantly decreased leakage currents and excellent device stability in ambient condition. Because our approach of combining soluble transition metal oxide (TMO) and polymeric acid shows dramatically better performance than pristine TMO, we expect that it can provide useful guidelines for the synthesis and application of TMOs for organic electronics in the future.
