TiO2 hierarchical pores/nanorod arrays composite film as photoanode for quantum dot-sensitized solar cells

Power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSSCs) was boosted in a TiO 2 composite film (TCSF) with delicate design in structure where TiO 2 hierarchical porous film (THPF) situated on the top of TiO 2 nanorod arrays film (TNAF). In this case, TNAF could supply efficient scattering centers for high light harvesting and direct electrical pathways for fast electron transfer while the THPF could offer porous channels for loading high quantity of previously synthetized quantum dots (QDs) and facilitate the penetration of electrolyte. Meanwhile, in this specific configuration, the presence of anatase–rutile heterojunction at the interface could help the rutile TNAF layer to efficiently collect photo-injected electrons from the anatase THPF layer thus suppressing the recombination of electrons and holes in electrolyte. The results showed that the PCE of QDSSC based on the TNAF photoanode was about 1.4-fold higher ( η  = 3.05%, J sc  = 15.86 mA cm −2 , V oc  = 0.602 V, FF = 0.319) than that of device based on pure THPF ( η  = 2.20%, J sc  = 13.82 mA cm −2 , V oc  = 0.572 V, FF = 0.278).