PbS Sensitized TiO2 Based Quantum Dot Solar Cells with Efficiency Greater Than 5% under Artificial Light: Effect of Compact Layer and Surface Passivation
Abstract
Nowdays, quantum dot sensitized solar cells have fascinated a great deal of interest due to its advantages that include high molar extinction coefficient tunable energy gaps, and multiple exciton generation of quantum dots. In this present work, the linker free approach was used to sensitize TiO2 photoelectrodes with PbS QDs by successive ionic layer adsorption and reaction at room temperature. The photovoltaic performance was evaluated using J-V characteristics with polysulphide as electrolyte and carbon composite molybdenum oxide as a counter electrode using Keithley Source meter under white light (30 mW/cm2) supplied from LED source. Electrochemical impedance spectroscopy is also used to measure the electron life time of the devices using Potentiostat/Galvanostat. Maximum efficiency of 5.82 % was recorded under artificial light with addition of TiO2 compact layer prior to porous TiO2 followed by surface passivation of PbS using ZnS, which corresponds to ~3 fold enhancement to that of device fabricated using bare TiO2.