Tuning the Optical and Structural Properties of Halide Perovskite by PbS Quantum Dot Additive Engineering for Enhanced Photovoltaic Performances

The combination of inorganic PbS quantum dots (QDs) and lead halide perovskite in one nanocomposite is considered as a promising approach to overcoming the limitations of metastable perovskites. However, to date, only a few examples of improved optoelectronic perovskites are realized with such materials. One of the keys to unraveling the full potential offered by the PbS QDs/perovskite material is the ability to purposefully modulate the interfacial electronic energy levels by changing the PbS QDs capping shell. Herein, this approach to adjust the offsets of the energy levels of the perovskite is demonstrated. To prepare the perovskite films with embedded PbS QDs, the organic capping of QDs is exchanged by a halide perovskite shell. Film properties are correlated to the structural changes of the soft perovskite matrix and their optical properties. Interestingly, this approach can be used to adjust the energy levels in the whole nanocomposite film, without changing the original bandgap, and thus paves the way for novel functional materials for optoelectronic devices. The applicability of this method is exemplified by fabricating solar cells with the perovskite nanocomposite, observing that the introduction of PbS/FAPI QDs into FAPI matrix boosts the average performance from 17.9% to 18.9% (21.3% champion device).