Self-assembled CdS quantum dots-sensitized TiO2 nanospheroidal solar cells: Structural and charge transport analysis

A nanospheroidal TiO2 mesoporous layer combined with cadmium sulfide (CdS) quantum dots (QDs) as a sensitizer was firstly utilized for solar cell applications, resulting in an efficiency of 1.2% at a 1 sun condition. CdS quantum dots (∼18 nm) were attached to the TiO2 nanospheroidal electrode by using a chemical bath deposition technique. The influence of surface treatment using dimethyl formamide on the interconnectivity of the TiO2 nanospheroidal electrodes was investigated. The charge transport of TiO2/CdS QDs/electrolyte sandwich-type cells was characterized by electrochemical impedance spectroscopy and the device performance was compared with conventional nanospherical TiO2 (Degauusa P25) electrodes. The electrodes with nanospheroidal morphology showed better device performance than the P25 nanoparticle electrodes primarily due to both better connectivity among nanospheroidal TiO2 particles and larger mesopores, resulting in deeper penetration of the electrolyte in QD-sensitized solar cells.