Core/CdS Quantum Dot/Shell Mesoporous Solar Cells with Improved Stability and Efficiency Using an Amorphous TiO2 Coating

Here we present a US quantum dot sensitized solar cell based on a mesoporous TiO2 film with remarkable stability using I-/I-3(-) electrolyte. Chemical Bath Deposition (CBD) was used to deposit the US quantum dots within the porous network. We show that a thin coating of the QD sensitized film with an amorphous TiO2 layer strongly improves the performance and photostability of the solar cell. We propose that the coating passivates QD surface states which act as hole traps and are responsible for photodegradation of the device. In addition, this coating decreases the recombination of electrons from the US quantum dots and the mesoporous TiO2 into the electrolyte solution. We obtain a significant improvement of all cell parameters resulting in a total light to electric power conversion efficiency of 1.24%.