Crystallization Retardation and Synergistic Trap Passivation in Perovskite Solar Cells Incorporated with Magnesium-Decorated Graphene Quantum Dots

[Image: see text] One of the encouraging strategies for enhancing the efficiency of perovskite solar cells (PSCs) is to reduce defects, trap states of pinholes, and charge recombination rate in the light absorber layer of perovskite, which can be addressed by increasing the perovskite grain size. The utilization of Mg-decorated graphene quantum dots (MGQD) or graphene quantum dots (GQDs) into a perovskite precursor solution for further crystal modification is introduced in this study. Studies on the crystalline structure and morphology of MGQD generated from GQDs demonstrate that MGQD has a greater crystal size than GQD. Therefore, higher light absorption in the whole UV–vis spectrum and a larger grain size for the perovskite/MGQD layer compared to the perovskite/GQD sample are achieved. Moreover, more photoluminescence peak quenching of perovskite/MGQD and extended carrier recombination lifetime (from 3 to 40 ns) verify the surface and grain boundary trap passivation compared to pristine perovskite. Consequently, PSCs in an n-i-p configuration containing perovskite/MGQD show a higher performance of 10.2% in comparison to the pristine perovskite at 7.2%, attributed to the enhanced J(SC) from 13.2 to 19.1 mA cm(–2). Thus, incorporating MGQDs into the perovskite layer is a hopeful approach for obtaining a superior perovskite film with impressive charge extraction and decreased nonradiative charge recombination.