Performance Improvement of Perovskite Solar Cells by Interactions between Nano-Sized Quantum Dots and Perovskite

Perovskite solar cells (PSCs) have undergone rapid progress and attracted considerable attention as a promising alternative to conventional photovoltaics but currently still face the challenges of Shockley-Queisser (SQ) limit and stability. Herein, the use of quantum dots (QDs) for the advancement of PSCs is focused on. The interactions between QDs and perovskite are discussed in terms of energy and charge transfer. The effective strategies for performance improvement of devices treated with QDs are interpreted from the point of view of surface modification (passivation and mixing), and microstructure (buffer function) and nanostructure (core/shell structure). In particular, possible routes to success in surpassing the SQ limit are summarized in association with the corresponding mechanisms. Also, the mechanisms for the enhancement of stability by QD treatment are analyzed, including quantum confinement effect, crystallization, ion migration inhibition, hydrophobicity improvement, passivation, and decomposition suppression. In addition, application of QDs to charge transporting layers is introduced and the resultant changes in device performance and stability are pointed out. The insights gained from this review are very crucial for the further advancement of PSCs treated with QDs.