Hierarchical TiO2 Nanostructured Array/P3HT Hybrid Solar Cells with Interfacial Modification

In this work, ordered hybrid polymer solar cells have been fabricated using rutile TiO2 nanoarchitecture arrays, i.e., nanorod (NR) and nanodendrite (ND) arrays, and poly(3-hexylthiophene) (P3HT). The performance of the rutile TiO2 NR/P3HT hybrid solar cell is significantly improved through interface modification with Z907 or D149 dye molecules. The enhancement of open-circuit voltage is attained in the dye-modified hybrid solar cell, which may be attributed to the lowering of the work function of the TiO2 NR array by dye adsorption. In addition to be the photocurrent contributor, the dye molecule plays a crucial role in the interface morphology of the TiO2 NR/P3HT hybrid. Z907 and D149 dye molecules not only provide an appropriate band alignment in between P3HT/TiO2 NR but also improve the compatibility of interface morphology of the hybrid. Charge separation and electron lifetime are therefore improved in the dye-modified TiO2 NRs/P3HT hybrid solar cells, resulting in the enrichments of the cell performances. Three-dimensional TiO2 ND arrays are further employed to enlarge the interface area of the ordered heterojunction hybrid solar cell. Compared to the D149-modified TiO2 NR/P3HT hybrid solar cell, considerable enhancement of charge separation is observed in the D149-modified TiO2 ND/P3HT solar cell. A notable efficiency of 3.12% is therefore achieved in the D149-modified TiO2 ND array/P3HT hybrid solar cell.