Agradecimentos: The Article Processing Charge for the publication of this research was funded by the Coordination for the Improvement of Higher Education Personnel - CAPES (ROR identifier: 00x0ma614). AFVF, LS, and BRCV thank São Paulo Research Foundation (FAPESP) under the grants (2023/10395-4, 2020/04406-5, and 2020/16077-6, respectively). MGDG thanks CNPq for the scholarship (142486/2020-5). ZCB and LFZ thank FAPESP under the grants (2023/09924-2 and 2021/06893-3, respectively). LAP acknowledges the support from the FAPESP (grant no. 2018/15574-6). AFN acknowledges the support from the FAPESP (grant no. 2017/11986-5) and Shell and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas, and Biofuels Agency) Ver menos

Abstract: Perovskite solar cells (PSCs) show promise for future photovoltaic technology. However, it faces challenges in terms of environmental stability. To address this, researchers have proposed nanomaterials such as perovskite quantum dots (QDs) to passivate the perovskite interfaces and enhance their stability. We explore the halide exchange reaction at the heterojunction between QDs and bulk (3D) perovskites using in situ photoluminescence. By determining the activation energy for the interfacial bromide-to-iodide exchange, we find that it is effective in passivating the 3D surface defects and grain boundaries. When applied in solar cells, QDs have energy level realignment, improving hole extraction and blocking electron transfer, which reduces bimolecular charge carrier recombination, thus increasing efficiency. The interfacial halide composition remains stable under thermal stress, and the QDs' ligand hydrophobicity was found to prevent moisture permeation within the perovskite films. Thus, strategically incorporating QDs enhances photovoltaic performance and has the potential to mitigate moisture and thermal-induced degradation Ver menos