ABSTRACT
The atomic layer deposition (ALD) of Al2O3 between perovskite and the hole transporting material (HTM) PEDOT:PSS has previously been shown to improve the efficiency of perovskite solar cells. However, the costs associated with this technique make it unaffordable. In this work, the deposition of an organic-inorganic PEDOT:PSS-Cl-Al2O3 bilayer is performed by a simple electrochemical technique with a final annealing step, and the performance of this material as HTM in inverted perovskite solar cells is studied. It was found that this material (PEDOT:PSS-Al2O3) improves the solar cell performance by the same mechanisms as Al2O3 obtained by ALD: formation of an additional energy barrier, perovskite passivation, and increase in the open-circuit voltage (Voc) due to suppressed recombination. As a result, the incorporation of the electrochemical Al2O3 increased the cell efficiency from 12.1% to 14.3%. Remarkably, this material led to higher steady-state power conversion efficiency, improving a recurring problem in solar cells.
ABSTRACT
α-CsPbI3 quantum dots (QDs) show outstanding photoelectrical properties that had been harnessed in the fabrication of perovskite QDs solar cells. Nevertheless, the stabilization of the CsPbI3 perovskite cubic phase remains a challenge due to its own thermodynamic and the presence of surface defects. Herein, we report the optimization of the CsPbI3 QDs solar cells, by monitoring the structure, the morphology and the optoelectronic properties after a precise treatment, consisting of the conventional solvent washing with a time limited ultraviolet (UV) exposure combination, during the layer-by-layer deposition. The UV treatment compensates the defects coming from the essential but deleterious washing treatment. The material is stable for 200 h and the PCE improved by the 25% compared with that of the device without UV treatment. The photo-enhanced ion mobility mechanism is discussed as the main process for the CsPbI3 QDs and solar cell stability.
