Enhancing the Performance of Sensitized Solar Cells with PbS/CH₃NH₃PbI₃ Core/Shell Quantum Dots

PSS). The PbS/MAP core/shell QDs were in situ-deposited by a modified successive ionic layer adsorption and reaction (SILAR) process using PbI2 and Na2S solutions with repeated spin-coating and subsequent dipping into CH3NH3I (=MAI) solution in the final stage. The resulting device showed much higher efficiency as compared to PbS QD-sensitized solar cells without a MAP shell layer, reaching an overall efficiency of 3.2% under simulated solar illumination (AM1.5, 100 mW·cm(-2)). From the measurement of the impedance spectroscopy and the time-resolved photoluminescence (PL) decay, the significantly enhanced performance is mainly attributed to both reduced charge recombination and better charge extraction by MAP shell layer. In addition, we demonstrate that the MAP shell effectively prevented the photocorrosion of PbS, resulting in highly improved stability in the cell efficiency with time. Therefore, our approach provides method for developing high performance QD-sensitized solar cells.